PyPy is an alternative implementation of the Python language that includes a JIT compiler for faster execution. However, when calling C extension functions from Python, PyPy experiences performance issues due to the use of a different object and memory representation. To address this, the author proposes a solution called HPy, which aims to improve the performance of PyPy’s C API interactions. The author suggests a method to add type information to C extension modules without changing the existing C API or ABI. This approach could potentially speed up C API calls and improve the performance of Python programs using PyPy.
https://bernsteinbear.com//blog/typed-c-extensions/