You have to be reaaaaaally slow to be beaten by a network. Also, touched by the OP, if it takes 3 hours to write some code that in Python takes only 1, or if the compile times are huge, Python can beat other languages in speed (that edge fades when the same program is used over and over again).
But as demonstrated, Nim is fast to write and fast to compile, so Python has little edge. Just it's huge ecosystem.