Numpy does have a lot of C code compared to most python packages, but I don't think that's the right way to look at it. If numpy was only about something being

Numpy does have a lot of C code compared to most python packages, but I don't think that's the right way to look at it. If numpy was only about something being in C instead of python, it would not be that interesting. But numpy brings you abstractions on top of python which are useful and even more high level than python, and that's what is interesting: abstractions which do make your code faster (when applicable, of course). From the blog's profiling posts, a lot of time seems to be spent into MDCT and polyphase decoding: both could be coded quite efficiently in numpy (I hope to add MDCT itself in scipy, actually). About being part of python: I don't think it would be a right move (and has been given up from both python and numpy), because numpy is quite big, and depends on quite hairy dependencies if you care about speed. I don't think it is fair to say that numpy is a language extension - numpy feels more natural than say twisted from a python integration POV. But I am a numpy developer, so maybe not the best judge.