Poor performance of concatList Value() method

[hzhaop]

hi, all,

expression: data.map(item, item.id)
input:
{"data": [{"id": "1"}, {"id": "2"}, ... , {"id": "1000"}]}

I call the Value() method of the program.Eval() output, find it very slow to return the value.

I find out that it's because data.map(item, item.id) produce a concatList, which is very slow in Value() method. (about O(N^2) complexity)

Is there any workaround method that I could enhance this expression performance?

[TristonianJones]

#491 should improve evaluation speed by 40x and ensure that the call to Value() is a constant time operation. The combination of the two effects should yield an even more significant performance boost for this use case.