Is there any significant performance penalty using WM built in Python?
All the heavy lifting is offloaded to C libraries. So, no, you shouldn't see a significant performance penalty, unless your Python WM is doing bitcoin mining in the background or something.
So no, do not expect a significant performance penalty.
And the differences between value types, AOT compiled code execution, bytecode interpreters and FFI marshalling costs between bytecode interpreters and native libraries.