> as long as the heavy work is done by calling native non-Python code.

Do not merge that. I once realized that grep is really fast, and replaced our custom solution with bash script, but I still claim that app is written in idiomatic PHP/python/ruby. This project has a lot of problems that it depends on C code is only a symptom. Noting all those bad things in a project Readme is a trap I fall into way to often it never works.