Cython is surprisingly nice (though techincally it generates C extensions). I was scared away from it, thinking it'd be yet another thing to learn and I could just use C if I really wanted to. But no, it's actually much easier to use than C for python interop. The only painful part for me was making sure that my extension code was recompiled and reloaded when I changed something, which I think stemmed to my lack of understanding of the python module building system.