Games aren't written in Python as a whole, but Python is used as a scripting language. It's definitely less popular now than it used to be, mostly thanks to Lua, but it still happens.

How many games use python for scripting and stay up to date with the version of python they're embedding? My guess is zero.

Doesn't seem all that relevant? New games will benefit from faster Python.

Indeed, but the question was about performance in general.