diff --git a/benchmarks/CMakeLists.txt b/benchmarks/CMakeLists.txt
index 4ab939351..3c00ccda1 100644
--- a/benchmarks/CMakeLists.txt
+++ b/benchmarks/CMakeLists.txt
@@ -41,3 +41,8 @@ foreach(BENCHMARK_SOURCE IN ITEMS ${BENCHMARK_SOURCES})
       $<TARGET_FILE_DIR:${BENCHMARK_EXECUTABLE}>)
   endif()
 endforeach()
+
+option(XLNT_MICROBENCH_ENABLED "Enable small benchmarks typically used for development" OFF)
+if (XLNT_MICROBENCH_ENABLED)
+	add_subdirectory(microbenchmarks)
+endif()
\ No newline at end of file
diff --git a/benchmarks/microbenchmarks/CMakeLists.txt b/benchmarks/microbenchmarks/CMakeLists.txt
new file mode 100644
index 000000000..745df1b82
--- /dev/null
+++ b/benchmarks/microbenchmarks/CMakeLists.txt
@@ -0,0 +1,36 @@
+# FetchContent added in cmake v3.11
+# https://cmake.org/cmake/help/v3.11/module/FetchContent.html
+# this file is behind a feature flag (XLNT_MICROBENCH_ENABLED) so the primary build is not affected
+cmake_minimum_required(VERSION 3.11)
+project(xlnt_ubench)
+
+# acquire google benchmark dependency
+# disable generation of the various test projects
+set(BENCHMARK_ENABLE_TESTING OFF)
+# gtest not required
+set(BENCHMARK_ENABLE_GTEST_TESTS OFF)
+
+include(FetchContent)
+FetchContent_Declare(
+	googlebenchmark
+	GIT_REPOSITORY 	https://github.com/google/benchmark
+	GIT_TAG			v1.5.0
+)
+# download if not already present
+FetchContent_GetProperties(googlebenchmark)
+if(NOT googlebenchmark_POPULATED)
+	FetchContent_Populate(googlebenchmark)
+	add_subdirectory(${googlebenchmark_SOURCE_DIR} ${googlebenchmark_BINARY_DIR})
+endif()
+# equivalent of add_subdirectory, now available for use
+FetchContent_MakeAvailable(googlebenchmark)
+
+
+add_executable(xlnt_ubench)
+target_sources(xlnt_ubench
+	PRIVATE
+		string_to_double.cpp
+		double_to_string.cpp
+)
+target_link_libraries(xlnt_ubench benchmark_main xlnt)
+target_compile_features(xlnt_ubench PRIVATE cxx_std_17)
\ No newline at end of file
diff --git a/benchmarks/microbenchmarks/double_to_string.cpp b/benchmarks/microbenchmarks/double_to_string.cpp
new file mode 100644
index 000000000..0b82803f6
--- /dev/null
+++ b/benchmarks/microbenchmarks/double_to_string.cpp
@@ -0,0 +1,207 @@
+// A core part of the xlsx serialisation routine is taking doubles from memory and stringifying them
+// this has a few requirements
+// - expect strings in the form 1234.56 (i.e. no thousands seperator, '.' used for the decimal seperator)
+// - outputs up to 15 significant figures (excel only serialises numbers up to 15sf)
+
+#include "benchmark/benchmark.h"
+#include <locale>
+#include <random>
+#include <sstream>
+
+namespace {
+
+// setup a large quantity of random doubles as strings
+template <bool Decimal_Locale = true>
+class RandomFloats : public benchmark::Fixture
+{
+    static constexpr size_t Number_of_Elements = 1 << 20;
+    static_assert(Number_of_Elements > 1'000'000, "ensure a decent set of random values is generated");
+
+    std::vector<double> inputs;
+
+    size_t index = 0;
+    const char *locale_str = nullptr;
+
+public:
+    void SetUp(const ::benchmark::State &state)
+    {
+        if (Decimal_Locale)
+        {
+            locale_str = setlocale(LC_ALL, "C");
+        }
+        else
+        {
+            locale_str = setlocale(LC_ALL, "de-DE");
+        }
+        std::random_device rd; // obtain a seed for the random number engine
+        std::mt19937 gen(rd());
+        // doing full range is stupid (<double>::min/max()...), it just ends up generating very large numbers
+        // uniform is probably not the best distribution to use here, but it will do for now
+        std::uniform_real_distribution<double> dis(-1'000, 1'000);
+        // generate a large quantity of doubles to deserialise
+        inputs.reserve(Number_of_Elements);
+        for (int i = 0; i < Number_of_Elements; ++i)
+        {
+            double d = dis(gen);
+            inputs.push_back(d);
+        }
+    }
+
+    void TearDown(const ::benchmark::State &state)
+    {
+        // restore locale
+        setlocale(LC_ALL, locale_str);
+        // gbench is keeping the fixtures alive somewhere, need to clear the data after use
+        inputs = std::vector<double>{};
+    }
+
+    double &get_rand()
+    {
+        return inputs[++index & (Number_of_Elements - 1)];
+    }
+};
+
+/// Takes in a double and outputs a string form of that number which will
+/// serialise and deserialise without loss of precision
+std::string serialize_number_to_string(double num)
+{
+    // more digits and excel won't match
+    constexpr int Excel_Digit_Precision = 15; //sf
+    std::stringstream ss;
+    ss.precision(Excel_Digit_Precision);
+    ss << num;
+    return ss.str();
+}
+
+class number_serialiser
+{
+    static constexpr int Excel_Digit_Precision = 15; //sf
+    std::ostringstream ss;
+
+public:
+    explicit number_serialiser()
+    {
+        ss.precision(Excel_Digit_Precision);
+        ss.imbue(std::locale("C"));
+    }
+
+    std::string serialise(double d)
+    {
+        ss.str(""); // reset string buffer
+        ss.clear(); // reset any error flags
+        ss << d;
+        return ss.str();
+    }
+};
+
+class number_serialiser_mk2
+{
+    static constexpr int Excel_Digit_Precision = 15; //sf
+    bool should_convert_comma;
+
+    void convert_comma(char *buf, int len)
+    {
+        char *buf_end = buf + len;
+        char *decimal = std::find(buf, buf_end, ',');
+        if (decimal != buf_end)
+        {
+            *decimal = '.';
+        }
+    }
+
+public:
+    explicit number_serialiser_mk2()
+        : should_convert_comma(std::use_facet<std::numpunct<char>>(std::locale{}).decimal_point() == ',')
+    {
+    }
+
+    std::string serialise(double d)
+    {
+        char buf[Excel_Digit_Precision + 1]; // need space for trailing '\0'
+        int len = snprintf(buf, sizeof(buf), "%.15g", d);
+        if (should_convert_comma)
+        {
+            convert_comma(buf, len);
+        }
+        return std::string(buf, len);
+    }
+};
+
+using RandFloats = RandomFloats<true>;
+using RandFloatsComma = RandomFloats<false>;
+} // namespace
+
+BENCHMARK_F(RandFloats, string_from_double_sstream)
+(benchmark::State &state)
+{
+    while (state.KeepRunning())
+    {
+        benchmark::DoNotOptimize(
+            serialize_number_to_string(get_rand()));
+    }
+}
+
+BENCHMARK_F(RandFloats, string_from_double_sstream_cached)
+(benchmark::State &state)
+{
+    number_serialiser ser;
+    while (state.KeepRunning())
+    {
+        benchmark::DoNotOptimize(
+            ser.serialise(get_rand()));
+    }
+}
+
+BENCHMARK_F(RandFloats, string_from_double_snprintf)
+(benchmark::State &state)
+{
+    while (state.KeepRunning())
+    {
+        char buf[16];
+        int len = snprintf(buf, sizeof(buf), "%.15g", get_rand());
+
+        benchmark::DoNotOptimize(
+            std::string(buf, len));
+    }
+}
+
+BENCHMARK_F(RandFloats, string_from_double_snprintf_fixed)
+(benchmark::State &state)
+{
+    number_serialiser_mk2 ser;
+    while (state.KeepRunning())
+    {
+        benchmark::DoNotOptimize(
+            ser.serialise(get_rand()));
+    }
+}
+
+// locale names are different between OS's, and std::from_chars is only complete in MSVC
+#ifdef _MSC_VER
+
+#include <charconv>
+BENCHMARK_F(RandFloats, string_from_double_std_to_chars)
+(benchmark::State &state)
+{
+    while (state.KeepRunning())
+    {
+        char buf[16];
+        std::to_chars_result result = std::to_chars(buf, buf + std::size(buf), get_rand());
+
+        benchmark::DoNotOptimize(
+            std::string(buf, result.ptr));
+    }
+}
+
+BENCHMARK_F(RandFloatsComma, string_from_double_snprintf_fixed_comma)
+(benchmark::State &state)
+{
+    number_serialiser_mk2 ser;
+    while (state.KeepRunning())
+    {
+        benchmark::DoNotOptimize(
+            ser.serialise(get_rand()));
+    }
+}
+
+#endif
\ No newline at end of file
diff --git a/benchmarks/microbenchmarks/string_to_double.cpp b/benchmarks/microbenchmarks/string_to_double.cpp
new file mode 100644
index 000000000..5392f0a25
--- /dev/null
+++ b/benchmarks/microbenchmarks/string_to_double.cpp
@@ -0,0 +1,223 @@
+// A core part of the xlsx parsing routine is taking strings from the xml parser and parsing these to a double
+// this has a few requirements
+// - expect strings in the form 1234.56 (i.e. no thousands seperator, '.' used for the decimal seperator)
+// - handles atleast 15 significant figures (excel only serialises numbers up to 15sf)
+
+#include <benchmark/benchmark.h>
+#include <locale>
+#include <random>
+#include <sstream>
+
+namespace {
+
+// setup a large quantity of random doubles as strings
+template <bool Decimal_Locale = true>
+class RandomFloatStrs : public benchmark::Fixture
+{
+    static constexpr size_t Number_of_Elements = 1 << 20;
+    static_assert(Number_of_Elements > 1'000'000, "ensure a decent set of random values is generated");
+
+    std::vector<std::string> inputs;
+
+    size_t index = 0;
+    const char *locale_str = nullptr;
+
+public:
+    void SetUp(const ::benchmark::State &state)
+    {
+        if (Decimal_Locale)
+        {
+            locale_str = setlocale(LC_ALL, "C");
+        }
+        else
+        {
+            locale_str = setlocale(LC_ALL, "de-DE");
+        }
+        std::random_device rd; // obtain a seed for the random number engine
+        std::mt19937 gen(rd());
+        // doing full range is stupid (<double>::min/max()...), it just ends up generating very large numbers
+        // uniform is probably not the best distribution to use here, but it will do for now
+        std::uniform_real_distribution<double> dis(-1'000, 1'000);
+        // generate a large quantity of doubles to deserialise
+        inputs.reserve(Number_of_Elements);
+        for (int i = 0; i < Number_of_Elements; ++i)
+        {
+            double d = dis(gen);
+            char buf[16];
+            snprintf(buf, 16, "%.15f", d);
+            inputs.push_back(std::string(buf));
+        }
+    }
+
+    void TearDown(const ::benchmark::State &state)
+    {
+        // restore locale
+        setlocale(LC_ALL, locale_str);
+        // gbench is keeping the fixtures alive somewhere, need to clear the data after use
+        inputs = std::vector<std::string>{};
+    }
+
+    std::string &get_rand()
+    {
+        return inputs[++index & (Number_of_Elements - 1)];
+    }
+};
+
+// method used by xlsx_consumer.cpp in commit - ba01de47a7d430764c20ec9ac9600eec0eb38bcf
+// std::istringstream with the locale set to "C"
+struct number_converter
+{
+    number_converter()
+    {
+        stream.imbue(std::locale("C"));
+    }
+
+    double stold(const std::string &s)
+    {
+        stream.str(s);
+        stream.clear();
+        stream >> result;
+        return result;
+    }
+
+    std::istringstream stream;
+    double result;
+};
+
+
+// to resolve the locale issue with strtod, a little preprocessing of the input is required
+struct number_converter_mk2
+{
+    explicit number_converter_mk2()
+        : should_convert_to_comma(std::use_facet<std::numpunct<char>>(std::locale{}).decimal_point() == ',')
+    {
+    }
+
+    double stold(std::string &s) const noexcept
+    {
+        assert(!s.empty());
+        if (should_convert_to_comma)
+        {
+            auto decimal_pt = std::find(s.begin(), s.end(), '.');
+            if (decimal_pt != s.end())
+            {
+                *decimal_pt = ',';
+            }
+        }
+        return strtod(s.c_str(), nullptr);
+    }
+
+    double stold(const std::string &s) const
+    {
+        assert(!s.empty());
+        if (!should_convert_to_comma)
+        {
+            return strtod(s.c_str(), nullptr);
+        }
+        std::string copy(s);
+        auto decimal_pt = std::find(copy.begin(), copy.end(), '.');
+        if (decimal_pt != copy.end())
+        {
+            *decimal_pt = ',';
+        }
+        return strtod(copy.c_str(), nullptr);
+    }
+
+private:
+    bool should_convert_to_comma = false;
+};
+
+using RandFloatStrs = RandomFloatStrs<true>;
+// german locale uses ',' as the seperator
+using RandFloatCommaStrs = RandomFloatStrs<false>;
+} // namespace
+
+BENCHMARK_F(RandFloatStrs, double_from_string_sstream)
+(benchmark::State &state)
+{
+    number_converter converter;
+    while (state.KeepRunning())
+    {
+        benchmark::DoNotOptimize(
+            converter.stold(get_rand()));
+    }
+}
+
+// using strotod
+// https://en.cppreference.com/w/cpp/string/byte/strtof
+// this naive usage is broken in the face of locales (fails condition 1)
+#include <cstdlib>
+BENCHMARK_F(RandFloatStrs, double_from_string_strtod)
+(benchmark::State &state)
+{
+    while (state.KeepRunning())
+    {
+        benchmark::DoNotOptimize(
+            strtod(get_rand().c_str(), nullptr));
+    }
+}
+
+BENCHMARK_F(RandFloatStrs, double_from_string_strtod_fixed)
+(benchmark::State &state)
+{
+    number_converter_mk2 converter;
+    while (state.KeepRunning())
+    {
+        benchmark::DoNotOptimize(
+            converter.stold(get_rand()));
+    }
+}
+
+BENCHMARK_F(RandFloatStrs, double_from_string_strtod_fixed_const_ref)
+(benchmark::State &state)
+{
+    number_converter_mk2 converter;
+    while (state.KeepRunning())
+    {
+        const std::string &inp = get_rand();
+        benchmark::DoNotOptimize(
+            converter.stold(inp));
+    }
+}
+
+// locale names are different between OS's, and std::from_chars is only complete in MSVC
+#ifdef _MSC_VER
+
+#include <charconv>
+BENCHMARK_F(RandFloatStrs, double_from_string_std_from_chars)
+(benchmark::State &state)
+{
+    while (state.KeepRunning())
+    {
+        const std::string &input = get_rand();
+        double output;
+        benchmark::DoNotOptimize(
+            std::from_chars(input.data(), input.data() + input.size(), output));
+    }
+}
+
+// not using the standard "C" locale with '.' seperator
+BENCHMARK_F(RandFloatCommaStrs, double_from_string_strtod_fixed_comma_ref)
+(benchmark::State &state)
+{
+    number_converter_mk2 converter;
+    while (state.KeepRunning())
+    {
+        benchmark::DoNotOptimize(
+            converter.stold(get_rand()));
+    }
+}
+
+BENCHMARK_F(RandFloatCommaStrs, double_from_string_strtod_fixed_comma_const_ref)
+(benchmark::State &state)
+{
+    number_converter_mk2 converter;
+    while (state.KeepRunning())
+    {
+        const std::string &inp = get_rand();
+        benchmark::DoNotOptimize(
+            converter.stold(inp));
+    }
+}
+
+#endif
\ No newline at end of file
diff --git a/benchmarks/spreadsheet-load.cpp b/benchmarks/spreadsheet-load.cpp
index 0caadb025..64318c791 100644
--- a/benchmarks/spreadsheet-load.cpp
+++ b/benchmarks/spreadsheet-load.cpp
@@ -5,7 +5,7 @@
 namespace {
 using milliseconds_d = std::chrono::duration<double, std::milli>;
 
-void run_test(const xlnt::path &file, int runs = 10)
+void run_load_test(const xlnt::path &file, int runs = 10)
 {
     std::cout << file.string() << "\n\n";
 
@@ -24,10 +24,35 @@ void run_test(const xlnt::path &file, int runs = 10)
         std::cout << milliseconds_d(test_timings.back()).count() << " ms\n";
     }
 }
+
+void run_save_test(const xlnt::path &file, int runs = 10)
+{
+    std::cout << file.string() << "\n\n";
+
+    xlnt::workbook wb;
+    wb.load(file);
+    const xlnt::path save_path(file.filename());
+
+    std::vector<std::chrono::steady_clock::duration> test_timings;
+
+    for (int i = 0; i < runs; ++i)
+    {
+        auto start = std::chrono::steady_clock::now();
+
+        wb.save(save_path);
+
+        auto end = std::chrono::steady_clock::now();
+        test_timings.push_back(end - start);
+        std::cout << milliseconds_d(test_timings.back()).count() << " ms\n";
+    }
+}
 } // namespace
 
 int main()
 {
-    run_test(path_helper::benchmark_file("large.xlsx"));
-    run_test(path_helper::benchmark_file("very_large.xlsx"));
+    run_load_test(path_helper::benchmark_file("large.xlsx"));
+    run_load_test(path_helper::benchmark_file("very_large.xlsx"));
+
+    run_save_test(path_helper::benchmark_file("large.xlsx"));
+    run_save_test(path_helper::benchmark_file("very_large.xlsx"));
 }
\ No newline at end of file
diff --git a/include/xlnt/cell/index_types.hpp b/include/xlnt/cell/index_types.hpp
index 2c14a0e00..1834d92e4 100644
--- a/include/xlnt/cell/index_types.hpp
+++ b/include/xlnt/cell/index_types.hpp
@@ -92,26 +92,11 @@ class XLNT_API column_t
     /// </summary>
     column_t(const char *column_string);
 
-    /// <summary>
-    /// Copy constructor. Constructs a column by copying it from other.
-    /// </summary>
-    column_t(const column_t &other);
-
-    /// <summary>
-    /// Move constructor. Constructs a column by moving it from other.
-    /// </summary>
-    column_t(column_t &&other);
-
     /// <summary>
     /// Returns a string representation of this column index.
     /// </summary>
     std::string column_string() const;
 
-    /// <summary>
-    /// Sets this column to be the same as rhs's and return reference to self.
-    /// </summary>
-    column_t &operator=(column_t rhs);
-
     /// <summary>
     /// Sets this column to be equal to rhs and return reference to self.
     /// </summary>
diff --git a/include/xlnt/utils/numeric.hpp b/include/xlnt/utils/numeric.hpp
index 28f37a909..cbf030949 100644
--- a/include/xlnt/utils/numeric.hpp
+++ b/include/xlnt/utils/numeric.hpp
@@ -34,21 +34,6 @@
 namespace xlnt {
 namespace detail {
 
-/// <summary>
-/// Takes in any number and outputs a string form of that number which will
-/// serialise and deserialise without loss of precision
-/// </summary>
-template <typename Number>
-std::string serialize_number_to_string(Number num)
-{
-    // more digits and excel won't match
-    constexpr int Excel_Digit_Precision = 15; //sf
-    std::stringstream ss;
-    ss.precision(Excel_Digit_Precision);
-    ss << num;
-    return ss.str();
-}
-
 /// <summary>
 /// constexpr abs
 /// </summary>
@@ -117,45 +102,72 @@ bool float_equals(const LNumber &lhs, const RNumber &rhs,
     return ((lhs + scaled_fuzz) >= rhs) && ((rhs + scaled_fuzz) >= lhs);
 }
 
-struct number_converter
+class number_serialiser
 {
-    explicit number_converter()
-        : should_convert_to_comma(std::use_facet<std::numpunct<char>>(std::locale{}).decimal_point() == ',')
+    static constexpr int Excel_Digit_Precision = 15; //sf
+    bool should_convert_comma;
+
+    static void convert_comma_to_pt(char *buf, int len)
     {
+        char *buf_end = buf + len;
+        char *decimal = std::find(buf, buf_end, ',');
+        if (decimal != buf_end)
+        {
+            *decimal = '.';
+        }
     }
 
-    double stold(std::string &s) const noexcept
+    static void convert_pt_to_comma(char *buf, size_t len)
+    {
+        char *buf_end = buf + len;
+        char *decimal = std::find(buf, buf_end, '.');
+        if (decimal != buf_end)
+        {
+            *decimal = ',';
+        }
+    }
+
+public:
+    explicit number_serialiser()
+        : should_convert_comma(std::use_facet<std::numpunct<char>>(std::locale{}).decimal_point() == ',')
+    {
+    }
+
+    std::string serialise(double d) const
+    {
+        char buf[30];
+        int len = snprintf(buf, sizeof(buf), "%.15g", d);
+        if (should_convert_comma)
+        {
+            convert_comma_to_pt(buf, len);
+        }
+        return std::string(buf, static_cast<size_t>(len));
+    }
+
+    double deserialise(std::string &s) const noexcept
     {
         assert(!s.empty());
-        if (should_convert_to_comma)
+        if (should_convert_comma)
         {
-            auto decimal_pt = std::find(s.begin(), s.end(), '.');
-            if (decimal_pt != s.end())
-            {
-                *decimal_pt = ',';
-            }
+            // s.data() doesn't have a non-const overload until c++17, hence this little dance
+            convert_pt_to_comma(&s[0], s.size());
         }
         return strtod(s.c_str(), nullptr);
     }
 
-    double stold(const std::string &s) const
+    double deserialise(const std::string &s) const
     {
         assert(!s.empty());
-        if (!should_convert_to_comma)
+        if (!should_convert_comma)
         {
             return strtod(s.c_str(), nullptr);
         }
-        std::string copy(s);
-        auto decimal_pt = std::find(copy.begin(), copy.end(), '.');
-        if (decimal_pt != copy.end())
-        {
-            *decimal_pt = ',';
-        }
-        return strtod(copy.c_str(), nullptr);
+        char buf[30];
+        assert(s.size() < sizeof(buf));
+        auto copy_end = std::copy(s.begin(), s.end(), buf);
+        convert_pt_to_comma(buf, static_cast<size_t>(copy_end - buf));
+        return strtod(buf, nullptr);
     }
-
-private:
-    bool should_convert_to_comma = false;
 };
 
 } // namespace detail
diff --git a/include/xlnt/worksheet/range_reference.hpp b/include/xlnt/worksheet/range_reference.hpp
index 76ba94cf3..907854a8d 100644
--- a/include/xlnt/worksheet/range_reference.hpp
+++ b/include/xlnt/worksheet/range_reference.hpp
@@ -69,8 +69,6 @@ class XLNT_API range_reference
     range_reference(column_t column_index_start, row_t row_index_start,
         column_t column_index_end, row_t row_index_end);
 
-    range_reference(const range_reference &ref);
-
     /// <summary>
     /// Returns true if the range has a width and height of 1 cell.
     /// </summary>
@@ -151,11 +149,6 @@ class XLNT_API range_reference
     /// </summary>
     bool operator!=(const char *reference_string) const;
 
-    /// <summary>
-    /// Assigns the extents of the provided range to this range.
-    /// </summary>
-    range_reference &operator=(const range_reference &ref);
-
 private:
     /// <summary>
     /// The top left cell in the range
diff --git a/source/cell/cell.cpp b/source/cell/cell.cpp
index ef6e7b241..e47f2a939 100644
--- a/source/cell/cell.cpp
+++ b/source/cell/cell.cpp
@@ -199,7 +199,7 @@ cell::cell(detail::cell_impl *d)
 
 bool cell::garbage_collectible() const
 {
-    return !(has_value() || is_merged() || phonetics_visible() || has_formula() || has_format() || has_hyperlink());
+    return d_->is_garbage_collectible();
 }
 
 void cell::value(std::nullptr_t)
diff --git a/source/cell/index_types.cpp b/source/cell/index_types.cpp
index 3c306a004..cecc6b0e3 100644
--- a/source/cell/index_types.cpp
+++ b/source/cell/index_types.cpp
@@ -109,27 +109,11 @@ column_t::column_t(const char *column_string)
 {
 }
 
-column_t::column_t(const column_t &other)
-    : column_t(other.index)
-{
-}
-
-column_t::column_t(column_t &&other)
-{
-    swap(*this, other);
-}
-
 std::string column_t::column_string() const
 {
     return column_string_from_index(index);
 }
 
-column_t &column_t::operator=(column_t rhs)
-{
-    swap(*this, rhs);
-    return *this;
-}
-
 column_t &column_t::operator=(const std::string &rhs)
 {
     return *this = column_t(rhs);
diff --git a/source/detail/header_footer/header_footer_code.cpp b/source/detail/header_footer/header_footer_code.cpp
index f7560eb82..014234de0 100644
--- a/source/detail/header_footer/header_footer_code.cpp
+++ b/source/detail/header_footer/header_footer_code.cpp
@@ -27,7 +27,7 @@
 namespace xlnt {
 namespace detail {
 
-std::array<xlnt::optional<xlnt::rich_text>, 3> decode_header_footer(const std::string &hf_string)
+std::array<xlnt::optional<xlnt::rich_text>, 3> decode_header_footer(const std::string &hf_string, const number_serialiser &serialiser)
 {
     std::array<xlnt::optional<xlnt::rich_text>, 3> result;
 
@@ -216,7 +216,7 @@ std::array<xlnt::optional<xlnt::rich_text>, 3> decode_header_footer(const std::s
         tokens.push_back(token);
     }
 
-    const auto parse_section = [&tokens, &result](hf_code code) {
+    const auto parse_section = [&tokens, &result, &serialiser](hf_code code) {
         std::vector<hf_code> end_codes{hf_code::left_section, hf_code::center_section, hf_code::right_section};
         end_codes.erase(std::find(end_codes.begin(), end_codes.end(), code));
 
@@ -297,7 +297,7 @@ std::array<xlnt::optional<xlnt::rich_text>, 3> decode_header_footer(const std::s
                     current_run.second = xlnt::font();
                 }
 
-                current_run.second.get().size(std::stod(current_token.value));
+                current_run.second.get().size(serialiser.deserialise(current_token.value));
 
                 break;
             }
@@ -460,7 +460,7 @@ std::array<xlnt::optional<xlnt::rich_text>, 3> decode_header_footer(const std::s
     return result;
 }
 
-std::string encode_header_footer(const rich_text &t, header_footer::location where)
+std::string encode_header_footer(const rich_text &t, header_footer::location where, const number_serialiser &serialiser)
 {
     const auto location_code_map =
         std::unordered_map<header_footer::location,
@@ -505,7 +505,7 @@ std::string encode_header_footer(const rich_text &t, header_footer::location whe
             if (run.second.get().has_size())
             {
                 encoded.push_back('&');
-                encoded.append(serialize_number_to_string(run.second.get().size()));
+                encoded.append(serialiser.serialise(run.second.get().size()));
             }
             if (run.second.get().underlined())
             {
diff --git a/source/detail/header_footer/header_footer_code.hpp b/source/detail/header_footer/header_footer_code.hpp
index 4556cf097..8fe15a98d 100644
--- a/source/detail/header_footer/header_footer_code.hpp
+++ b/source/detail/header_footer/header_footer_code.hpp
@@ -27,12 +27,13 @@
 #include <xlnt/cell/rich_text.hpp>
 #include <xlnt/utils/optional.hpp>
 #include <xlnt/worksheet/header_footer.hpp>
+#include <xlnt/utils/numeric.hpp>
 
 namespace xlnt {
 namespace detail {
 
-std::array<xlnt::optional<xlnt::rich_text>, 3> decode_header_footer(const std::string &hf_string);
-std::string encode_header_footer(const rich_text &t, header_footer::location where);
+std::array<xlnt::optional<xlnt::rich_text>, 3> decode_header_footer(const std::string &hf_string, const number_serialiser &serialiser);
+std::string encode_header_footer(const rich_text &t, header_footer::location where, const number_serialiser& serialiser);
 
 } // namespace detail
 } // namespace xlnt
diff --git a/source/detail/implementations/cell_impl.hpp b/source/detail/implementations/cell_impl.hpp
index 52e594443..110974147 100644
--- a/source/detail/implementations/cell_impl.hpp
+++ b/source/detail/implementations/cell_impl.hpp
@@ -47,7 +47,7 @@ struct cell_impl
     cell_impl(cell_impl &&other) = default;
     cell_impl &operator=(const cell_impl &other) = default;
     cell_impl &operator=(cell_impl &&other) = default;
-    
+
     cell_type type_;
 
     worksheet_impl *parent_;
@@ -65,6 +65,11 @@ struct cell_impl
     optional<hyperlink_impl> hyperlink_;
     optional<format_impl *> format_;
     optional<comment *> comment_;
+
+    bool is_garbage_collectible() const
+    {
+        return !(type_ != cell_type::empty || is_merged_ || phonetics_visible_ || formula_.is_set() || format_.is_set() || hyperlink_.is_set());
+    }
 };
 
 inline bool operator==(const cell_impl &lhs, const cell_impl &rhs)
diff --git a/source/detail/serialization/xlsx_consumer.cpp b/source/detail/serialization/xlsx_consumer.cpp
index ea64b1318..bde76349f 100644
--- a/source/detail/serialization/xlsx_consumer.cpp
+++ b/source/detail/serialization/xlsx_consumer.cpp
@@ -307,14 +307,14 @@ Cell parse_cell(xlnt::row_t row_arg, xml::parser *parser)
 }
 
 // <row> inside <sheetData> element
-std::pair<xlnt::row_properties, int> parse_row(xml::parser *parser, xlnt::detail::number_converter &converter, std::vector<Cell> &parsed_cells)
+std::pair<xlnt::row_properties, int> parse_row(xml::parser *parser, xlnt::detail::number_serialiser &converter, std::vector<Cell> &parsed_cells)
 {
     std::pair<xlnt::row_properties, int> props;
     for (auto &attr : parser->attribute_map())
     {
         if (string_equal(attr.first.name(), "dyDescent"))
         {
-            props.first.dy_descent = converter.stold(attr.second.value);
+            props.first.dy_descent = converter.deserialise(attr.second.value);
         }
         else if (string_equal(attr.first.name(), "spans"))
         {
@@ -322,7 +322,7 @@ std::pair<xlnt::row_properties, int> parse_row(xml::parser *parser, xlnt::detail
         }
         else if (string_equal(attr.first.name(), "ht"))
         {
-            props.first.height = converter.stold(attr.second.value);
+            props.first.height = converter.deserialise(attr.second.value);
         }
         else if (string_equal(attr.first.name(), "s"))
         {
@@ -382,7 +382,7 @@ std::pair<xlnt::row_properties, int> parse_row(xml::parser *parser, xlnt::detail
 }
 
 // <sheetData> inside <worksheet> element
-Sheet_Data parse_sheet_data(xml::parser *parser, xlnt::detail::number_converter &converter)
+Sheet_Data parse_sheet_data(xml::parser *parser, xlnt::detail::number_serialiser &converter)
 {
     Sheet_Data sheet_data;
     int level = 1; // nesting level
@@ -480,7 +480,7 @@ cell xlsx_consumer::read_cell()
 
         if (parser().attribute_present("ht"))
         {
-            row_properties.height = converter_.stold(parser().attribute("ht"));
+            row_properties.height = converter_.deserialise(parser().attribute("ht"));
         }
 
         if (parser().attribute_present("customHeight"))
@@ -495,7 +495,7 @@ cell xlsx_consumer::read_cell()
 
         if (parser().attribute_present(qn("x14ac", "dyDescent")))
         {
-            row_properties.dy_descent = converter_.stold(parser().attribute(qn("x14ac", "dyDescent")));
+            row_properties.dy_descent = converter_.deserialise(parser().attribute(qn("x14ac", "dyDescent")));
         }
 
         if (parser().attribute_present("spans"))
@@ -602,7 +602,7 @@ cell xlsx_consumer::read_cell()
         }
         else if (type == "s")
         {
-            cell.d_->value_numeric_ = converter_.stold(value_string);
+            cell.d_->value_numeric_ = converter_.deserialise(value_string);
             cell.data_type(cell::type::shared_string);
         }
         else if (type == "b") // boolean
@@ -611,7 +611,7 @@ cell xlsx_consumer::read_cell()
         }
         else if (type == "n") // numeric
         {
-            cell.value(converter_.stold(value_string));
+            cell.value(converter_.deserialise(value_string));
         }
         else if (!value_string.empty() && value_string[0] == '#')
         {
@@ -863,23 +863,23 @@ std::string xlsx_consumer::read_worksheet_begin(const std::string &rel_id)
             if (parser().attribute_present("baseColWidth"))
             {
                 ws.d_->format_properties_.base_col_width =
-                    converter_.stold(parser().attribute("baseColWidth"));
+                    converter_.deserialise(parser().attribute("baseColWidth"));
             }
             if (parser().attribute_present("defaultColWidth"))
             {
                 ws.d_->format_properties_.default_column_width =
-                    converter_.stold(parser().attribute("defaultColWidth"));
+                    converter_.deserialise(parser().attribute("defaultColWidth"));
             }
             if (parser().attribute_present("defaultRowHeight"))
             {
                 ws.d_->format_properties_.default_row_height =
-                    converter_.stold(parser().attribute("defaultRowHeight"));
+                    converter_.deserialise(parser().attribute("defaultRowHeight"));
             }
 
             if (parser().attribute_present(qn("x14ac", "dyDescent")))
             {
                 ws.d_->format_properties_.dy_descent =
-                    converter_.stold(parser().attribute(qn("x14ac", "dyDescent")));
+                    converter_.deserialise(parser().attribute(qn("x14ac", "dyDescent")));
             }
 
             skip_attributes();
@@ -899,7 +899,7 @@ std::string xlsx_consumer::read_worksheet_begin(const std::string &rel_id)
                 optional<double> width = [this](xml::parser &p) -> xlnt::optional<double> {
                     if (p.attribute_present("width"))
                     {
-                        return (converter_.stold(p.attribute("width")) * 7 - 5) / 7;
+                        return (converter_.deserialise(p.attribute("width")) * 7 - 5) / 7;
                     }
                     return xlnt::optional<double>();
                 }(parser());
@@ -1000,7 +1000,7 @@ void xlsx_consumer::read_worksheet_sheetdata()
             case cell::type::empty:
             case cell::type::number:
             case cell::type::date: {
-                ws_cell_impl->value_numeric_ = converter_.stold(cell.value);
+                ws_cell_impl->value_numeric_ = converter_.deserialise(cell.value);
                 break;
             }
             case cell::type::shared_string: {
@@ -1196,12 +1196,12 @@ worksheet xlsx_consumer::read_worksheet_end(const std::string &rel_id)
         {
             page_margins margins;
 
-            margins.top(converter_.stold(parser().attribute("top")));
-            margins.bottom(converter_.stold(parser().attribute("bottom")));
-            margins.left(converter_.stold(parser().attribute("left")));
-            margins.right(converter_.stold(parser().attribute("right")));
-            margins.header(converter_.stold(parser().attribute("header")));
-            margins.footer(converter_.stold(parser().attribute("footer")));
+            margins.top(converter_.deserialise(parser().attribute("top")));
+            margins.bottom(converter_.deserialise(parser().attribute("bottom")));
+            margins.left(converter_.deserialise(parser().attribute("left")));
+            margins.right(converter_.deserialise(parser().attribute("right")));
+            margins.header(converter_.deserialise(parser().attribute("header")));
+            margins.footer(converter_.deserialise(parser().attribute("footer")));
 
             ws.page_margins(margins);
         }
@@ -1251,27 +1251,27 @@ worksheet xlsx_consumer::read_worksheet_end(const std::string &rel_id)
 
                 if (current_hf_element == qn("spreadsheetml", "oddHeader"))
                 {
-                    odd_header = decode_header_footer(read_text());
+                    odd_header = decode_header_footer(read_text(), converter_);
                 }
                 else if (current_hf_element == qn("spreadsheetml", "oddFooter"))
                 {
-                    odd_footer = decode_header_footer(read_text());
+                    odd_footer = decode_header_footer(read_text(), converter_);
                 }
                 else if (current_hf_element == qn("spreadsheetml", "evenHeader"))
                 {
-                    even_header = decode_header_footer(read_text());
+                    even_header = decode_header_footer(read_text(), converter_);
                 }
                 else if (current_hf_element == qn("spreadsheetml", "evenFooter"))
                 {
-                    even_footer = decode_header_footer(read_text());
+                    even_footer = decode_header_footer(read_text(), converter_);
                 }
                 else if (current_hf_element == qn("spreadsheetml", "firstHeader"))
                 {
-                    first_header = decode_header_footer(read_text());
+                    first_header = decode_header_footer(read_text(), converter_);
                 }
                 else if (current_hf_element == qn("spreadsheetml", "firstFooter"))
                 {
-                    first_footer = decode_header_footer(read_text());
+                    first_footer = decode_header_footer(read_text(), converter_);
                 }
                 else
                 {
@@ -2308,7 +2308,7 @@ void xlsx_consumer::read_stylesheet()
                     while (in_element(qn("spreadsheetml", "gradientFill")))
                     {
                         expect_start_element(qn("spreadsheetml", "stop"), xml::content::complex);
-                        auto position = converter_.stold(parser().attribute("position"));
+                        auto position = converter_.deserialise(parser().attribute("position"));
                         expect_start_element(qn("spreadsheetml", "color"), xml::content::complex);
                         auto color = read_color();
                         expect_end_element(qn("spreadsheetml", "color"));
@@ -2356,7 +2356,7 @@ void xlsx_consumer::read_stylesheet()
 
                     if (font_property_element == qn("spreadsheetml", "sz"))
                     {
-                        new_font.size(converter_.stold(parser().attribute("val")));
+                        new_font.size(converter_.deserialise(parser().attribute("val")));
                     }
                     else if (font_property_element == qn("spreadsheetml", "name"))
                     {
@@ -3169,7 +3169,7 @@ rich_text xlsx_consumer::read_rich_text(const xml::qname &parent)
 
                         if (current_run_property_element == xml::qname(xmlns, "sz"))
                         {
-                            run.second.get().size(converter_.stold(parser().attribute("val")));
+                            run.second.get().size(converter_.deserialise(parser().attribute("val")));
                         }
                         else if (current_run_property_element == xml::qname(xmlns, "rFont"))
                         {
@@ -3307,7 +3307,7 @@ xlnt::color xlsx_consumer::read_color()
 
     if (parser().attribute_present("tint"))
     {
-        result.tint(converter_.stold(parser().attribute("tint")));
+        result.tint(converter_.deserialise(parser().attribute("tint")));
     }
 
     return result;
diff --git a/source/detail/serialization/xlsx_consumer.hpp b/source/detail/serialization/xlsx_consumer.hpp
index 963e1361e..c9a987ee2 100644
--- a/source/detail/serialization/xlsx_consumer.hpp
+++ b/source/detail/serialization/xlsx_consumer.hpp
@@ -416,7 +416,7 @@ class xlsx_consumer
     detail::cell_impl *current_cell_;
 
     detail::worksheet_impl *current_worksheet_;
-    number_converter converter_;
+    number_serialiser converter_;
 };
 
 } // namespace detail
diff --git a/source/detail/serialization/xlsx_producer.cpp b/source/detail/serialization/xlsx_producer.cpp
index e0a52870e..1646b70bc 100644
--- a/source/detail/serialization/xlsx_producer.cpp
+++ b/source/detail/serialization/xlsx_producer.cpp
@@ -2267,16 +2267,18 @@ void xlsx_producer::write_worksheet(const relationship &rel)
         {
             write_attribute("enableFormatConditionsCalculation", props.enable_format_condition_calculation.get());
         }
-
+        // outlinePr is optional in the spec but is being written every time?
         write_start_element(xmlns, "outlinePr");
         write_attribute("summaryBelow", "1");
         write_attribute("summaryRight", "1");
         write_end_element(xmlns, "outlinePr");
 
-        write_start_element(xmlns, "pageSetUpPr");
-        write_attribute("fitToPage", write_bool(ws.page_setup().fit_to_page()));
-        write_end_element(xmlns, "pageSetUpPr");
-
+        if (ws.has_page_setup())
+        {
+            write_start_element(xmlns, "pageSetUpPr");
+            write_attribute("fitToPage", write_bool(ws.page_setup().fit_to_page()));
+            write_end_element(xmlns, "pageSetUpPr");
+        }
         write_end_element(xmlns, "sheetPr");
     }
 
@@ -2418,7 +2420,7 @@ void xlsx_producer::write_worksheet(const relationship &rel)
         if (props.width.is_set())
         {
             double width = (props.width.get() * 7 + 5) / 7;
-            write_attribute("width", serialize_number_to_string(width));
+            write_attribute("width", converter_.serialise(width));
         }
 
         if (props.best_fit)
@@ -2481,12 +2483,19 @@ void xlsx_producer::write_worksheet(const relationship &rel)
         {
             for (auto column = dimension.top_left().column(); column <= dimension.bottom_right().column(); ++column)
             {
-                if (!ws.has_cell(cell_reference(column, check_row))) continue;
-                auto cell = ws.cell(cell_reference(column, check_row));
-                if (cell.garbage_collectible()) continue;
+                auto ref = cell_reference(column, check_row);
+                auto cell = ws.d_->cell_map_.find(ref);
+                if (cell == ws.d_->cell_map_.end())
+                {
+                    continue;
+                }
+                if (cell->second.is_garbage_collectible())
+                {
+                    continue;
+                }
 
-                first_block_column = std::min(first_block_column, cell.column());
-                last_block_column = std::max(last_block_column, cell.column());
+                first_block_column = std::min(first_block_column, cell->second.column_);
+                last_block_column = std::max(last_block_column, cell->second.column_);
 
                 if (row == check_row)
                 {
@@ -2520,7 +2529,7 @@ void xlsx_producer::write_worksheet(const relationship &rel)
             if (props.height.is_set())
             {
                 auto height = props.height.get();
-                write_attribute("ht", serialize_number_to_string(height));
+                write_attribute("ht", converter_.serialise(height));
             }
 
             if (props.hidden)
@@ -2647,7 +2656,7 @@ void xlsx_producer::write_worksheet(const relationship &rel)
 
                 case cell::type::number:
                     write_start_element(xmlns, "v");
-                    write_characters(serialize_number_to_string(cell.value<double>()));
+                    write_characters(converter_.serialise(cell.value<double>()));
                     write_end_element(xmlns, "v");
                     break;
 
@@ -2884,26 +2893,26 @@ void xlsx_producer::write_worksheet(const relationship &rel)
             {
                 if (hf.has_odd_even_header(location))
                 {
-                    odd_header.append(encode_header_footer(hf.odd_header(location), location));
-                    even_header.append(encode_header_footer(hf.even_header(location), location));
+                    odd_header.append(encode_header_footer(hf.odd_header(location), location, converter_));
+                    even_header.append(encode_header_footer(hf.even_header(location), location, converter_));
                 }
 
                 if (hf.has_odd_even_footer(location))
                 {
-                    odd_footer.append(encode_header_footer(hf.odd_footer(location), location));
-                    even_footer.append(encode_header_footer(hf.even_footer(location), location));
+                    odd_footer.append(encode_header_footer(hf.odd_footer(location), location, converter_));
+                    even_footer.append(encode_header_footer(hf.even_footer(location), location, converter_));
                 }
             }
             else
             {
                 if (hf.has_header(location))
                 {
-                    odd_header.append(encode_header_footer(hf.header(location), location));
+                    odd_header.append(encode_header_footer(hf.header(location), location, converter_));
                 }
 
                 if (hf.has_footer(location))
                 {
-                    odd_footer.append(encode_header_footer(hf.footer(location), location));
+                    odd_footer.append(encode_header_footer(hf.footer(location), location, converter_));
                 }
             }
 
@@ -2911,12 +2920,12 @@ void xlsx_producer::write_worksheet(const relationship &rel)
             {
                 if (hf.has_first_page_header(location))
                 {
-                    first_header.append(encode_header_footer(hf.first_page_header(location), location));
+                    first_header.append(encode_header_footer(hf.first_page_header(location), location, converter_));
                 }
 
                 if (hf.has_first_page_footer(location))
                 {
-                    first_footer.append(encode_header_footer(hf.first_page_footer(location), location));
+                    first_footer.append(encode_header_footer(hf.first_page_footer(location), location, converter_));
                 }
             }
         }
@@ -3383,7 +3392,7 @@ void xlsx_producer::write_color(const xlnt::color &color)
     }
     if (color.has_tint())
     {
-        write_attribute("tint", serialize_number_to_string(color.tint()));
+        write_attribute("tint", converter_.serialise(color.tint()));
     }
 }
 
diff --git a/source/detail/serialization/xlsx_producer.hpp b/source/detail/serialization/xlsx_producer.hpp
index 296025b9c..4660f3c2d 100644
--- a/source/detail/serialization/xlsx_producer.hpp
+++ b/source/detail/serialization/xlsx_producer.hpp
@@ -30,6 +30,7 @@
 
 #include <detail/constants.hpp>
 #include <detail/external/include_libstudxml.hpp>
+#include <xlnt/utils/numeric.hpp>
 
 namespace xml {
 class serializer;
@@ -208,6 +209,7 @@ class xlsx_producer
     detail::cell_impl *current_cell_;
 
     detail::worksheet_impl *current_worksheet_;
+    detail::number_serialiser converter_;
 };
 
 } // namespace detail
diff --git a/source/worksheet/range_reference.cpp b/source/worksheet/range_reference.cpp
index c53a33efb..490cac55c 100644
--- a/source/worksheet/range_reference.cpp
+++ b/source/worksheet/range_reference.cpp
@@ -46,12 +46,6 @@ range_reference::range_reference(const char *range_string)
 {
 }
 
-range_reference::range_reference(const range_reference &ref)
-{
-    top_left_ = ref.top_left_;
-    bottom_right_ = ref.bottom_right_;
-}
-
 range_reference::range_reference(const std::string &range_string)
     : top_left_("A1"), bottom_right_("A1")
 {
@@ -183,11 +177,4 @@ XLNT_API bool operator!=(const char *reference_string, const range_reference &re
     return ref != reference_string;
 }
 
-range_reference &range_reference::operator=(const range_reference &ref)
-{
-    top_left_ = ref.top_left_;
-    bottom_right_ = ref.bottom_right_;
-    return *this;
-}
-
 } // namespace xlnt
diff --git a/source/worksheet/worksheet.cpp b/source/worksheet/worksheet.cpp
index 866f02076..bb7141e2a 100644
--- a/source/worksheet/worksheet.cpp
+++ b/source/worksheet/worksheet.cpp
@@ -579,8 +579,40 @@ column_t worksheet::highest_column_or_props() const
 
 range_reference worksheet::calculate_dimension() const
 {
-    return range_reference(lowest_column(), lowest_row_or_props(),
-        highest_column(), highest_row_or_props());
+    // partially optimised version of:
+    // return range_reference(lowest_column(), lowest_row_or_props(),
+    //                        highest_column(), highest_row_or_props());
+    //
+    if (d_->cell_map_.empty() && d_->row_properties_.empty())
+    {
+        return range_reference(constants::min_column(), constants::min_row(),
+            constants::min_column(), constants::min_row());
+    }
+    row_t min_row_prop = constants::max_row();
+    row_t max_row_prop = constants::min_row();
+    for (const auto &row_prop : d_->row_properties_)
+    {
+        min_row_prop = std::min(min_row_prop, row_prop.first);
+        max_row_prop = std::max(max_row_prop, row_prop.first);
+    }
+    if (d_->cell_map_.empty())
+    {
+        return range_reference(constants::min_column(), min_row_prop,
+            constants::min_column(), max_row_prop);
+    }
+    // find min and max row/column in cell map
+    column_t min_col = constants::max_column();
+    column_t max_col = constants::min_column();
+    row_t min_row = min_row_prop;
+    row_t max_row = max_row_prop;
+    for (auto &c : d_->cell_map_)
+    {
+        min_col = std::min(min_col, c.second.column_);
+        max_col = std::max(max_col, c.second.column_);
+        min_row = std::min(min_row, c.second.row_);
+        max_row = std::max(max_row, c.second.row_);
+    }
+    return range_reference(min_col, min_row, max_col, max_row);
 }
 
 range worksheet::range(const std::string &reference_string)
diff --git a/tests/detail/numeric_util_test_suite.cpp b/tests/detail/numeric_util_test_suite.cpp
index 1d8026bab..c2536f840 100644
--- a/tests/detail/numeric_util_test_suite.cpp
+++ b/tests/detail/numeric_util_test_suite.cpp
@@ -40,17 +40,18 @@ class numeric_test_suite : public test_suite
 
     void test_serialise_number()
     {
+        xlnt::detail::number_serialiser serialiser;
         // excel serialises numbers as floating point values with <= 15 digits of precision
-        xlnt_assert(xlnt::detail::serialize_number_to_string(1) == "1");
+        xlnt_assert(serialiser.serialise(1) == "1");
         // trailing zeroes are ignored
-        xlnt_assert(xlnt::detail::serialize_number_to_string(1.0) == "1");
-        xlnt_assert(xlnt::detail::serialize_number_to_string(1.0f) == "1");
+        xlnt_assert(serialiser.serialise(1.0) == "1");
+        xlnt_assert(serialiser.serialise(1.0f) == "1");
         // one to 1 relation
-        xlnt_assert(xlnt::detail::serialize_number_to_string(1.23456) == "1.23456");
-        xlnt_assert(xlnt::detail::serialize_number_to_string(1.23456789012345) == "1.23456789012345");
-        xlnt_assert(xlnt::detail::serialize_number_to_string(123456.789012345) == "123456.789012345");
-        xlnt_assert(xlnt::detail::serialize_number_to_string(1.23456789012345e+67) == "1.23456789012345e+67");
-        xlnt_assert(xlnt::detail::serialize_number_to_string(1.23456789012345e-67) == "1.23456789012345e-67");
+        xlnt_assert(serialiser.serialise(1.23456) == "1.23456");
+        xlnt_assert(serialiser.serialise(1.23456789012345) == "1.23456789012345");
+        xlnt_assert(serialiser.serialise(123456.789012345) == "123456.789012345");
+        xlnt_assert(serialiser.serialise(1.23456789012345e+67) == "1.23456789012345e+67");
+        xlnt_assert(serialiser.serialise(1.23456789012345e-67) == "1.23456789012345e-67");
     }
 
     void test_float_equals_zero()