If more than a few percent of execution time is spent in Python you are probably doing it wrong.
Personally I don't even understand why Cython is a thing, just write performance critical functions in other languages:
<https://pypi.org/project/rustimport/>
<https://pypi.org/project/import-zig/>
Note that you can even start threads in those languages and use function calls as pseudo-RPC. All without an overly complex build system.