[qeternity]

IIRC, PyPy is actually slower on pure CFFI calls, so anything that is mostly Numpy/Pandas/Scikit will likely be slower in PyPy. At least this was the case when we were using PyPy 3.5.

But often the rest of your code base will experience dramatic increases in performance, and the penalty on already fast CFFI calls was not significant overall (in our use case).

[fijal]

I think you are confusing CFFI (which is massively faster under pypy) with CPython C API calls (which is both slower under pypy and ones used by numpy)