为什么在嵌套函数之外声明计数器变量会使循环慢5倍?

I was looking for some micro optimizations of some JavaScript legacy code I was revisiting and noticed that in most frequently called for loops, counters were declared once in the global scope, outside the functions using them. I was curious whether that was indeed an optimization therefore I have created the following test case in JavaScript:I was looking for some micro optimizations of s