This doesn't directly answer your question, but I think a better use case for pybind11 is when you have an existing C++ library with a fairly rich typesystem and you want to expose it to Python.

If you just want to reimplement some parts of your code in C for performance (I'd argue you neither need nor want C++, you shouldn't bother with C++'s object system and you should keep using Python)'s, CFFI might be simpler:

https://cffi.readthedocs.io/en/latest/overview.html#purely-f...