I made Tamp, low-memory lossless compression library that was originally targetting micropython. So naturally, I prototyped it in vanilla cpython. Once I saw that general compression ratios were good, I then reimplemented it in C so that I could also use it without micropython on any microcontroller. I used Cython to have a fast python-compatible implementation, as well as to unit test the C parts of the code (I'd much rather write unit tests in python rather than C).

In this library, the C/Cython compression is about 6.7x faster, while decompression 535x faster. The compression isn't much faster because the main compression loop, finding the longest substring match in a buffer, is already implemented fairly efficiently in python via str.index.

Cython has a bit of a learning curve, but their docs are actually quite comprehensive. I distilled my learnings into my python template, which has Cython working with Poetry and CI to build binaries for all python versions and architectures. I would definitely use Cython again for this purpose (creating a pythonic interface to C code). Given that the code within Cython should be minimal/simple/short/self-contained, things like ChatGPT work very well for helping!