[dman]

CPython has numpy which rocks for number crunching.

[rbanffy]

And has no GIL problems.

[cdavid]

This is not exactly true. We can alleviate the GIL issue by releasing it inside C extensions, true, but it is still there nonetheless. Incidentally, one of the big advantage of the GIL is to make C extensions easier to write.

[rbanffy]

You can then call it The GIL Advantage ;-)

As long as you are not creating or destroying the Python objects you expect to give back to the Python side of your program, you don't have to care much about it.