Istvan Albert <istvan.albert at gmail.com> writes: > Now it takes over two minutes to do this: > > size = 10**7 > a = [ 0 ] * size > b = zip(a,a) OK, I'm getting similar results under 64 bit Pytnon 2.4.4c1 and also under 2.5. About 103 seconds for 10**7 and 26 seconds for 5*10**6. So it looks like zip is using quadratic time. I suggest entering a bug report.