Where does the performance boost of map or list comprehension implementations over calling a function over a loop come from?

Question

I understand that you could be more efficient with memory in the implementation of map than in how you might do it over a loop. However, I see that using a map function over

Answer 1

The difference is due to append, not map. Try this:

res = []
res = [square2(foo) for foo in foobar]