[topaz0]

It's obviously not python vs c -- the time difference turns out to be in kernel code (system call) and not user code at all, and the post explicitly constructs a c program that doesn't have the slowdown by adding a memory offset. It just turns up by default in a comparison of python vs c code because python reads have a memory offset by default (for completely unrelated reasons) and analogous c reads don't by default. In principle you could also construct python code that does see this slowdown, it would just be much less likely to show up at random. So the python vs c comp is a total red herring here, it just happened to be what the author noticed and used as a hook to understand the problem.