运行tools/quantization_tool/examples/example.py，生成的mnist_model_example_optimized.onnx推理速度更慢而且所占用空间更大，请问是为什么？ (AIV-608)

[1Yanxiaolin1]

打印出来的结果如下：
accuracy of int8 model is: 0.977000
accuracy of fp32 model is: 0.977000
int8-model test time is 1.8347067832946777
float-model test time is 0.36646580696105957
Size of mnist_model_example_optimized.onnx: 439206 bytes
Size of mnist_model_example.onnx: 439119 bytes
有没有高人指点一下这是为什么？？？感谢！！！

[sun-xiangyu]

please try new esp-dl