Except that Python has scipy,numpy and cython in its camp. I have spent the last six months of my life making Python code run faster. You can write slow code very quickly in Python. If your users complain about it being too slow you can implement some critical sections in Cython. (again with very minor changes). That being said there is a overhead to calling functions in Python which I would like addressed. (Dictionary lookups were three times as fast as function calls when I measured them).