>>> from timeit import timeit >>> setup = """ def join_list(limit): resp = [] for num in xrange(limit): resp.append(`num`) return ''.join(resp) """ >>> timeit(stmt='join_list(2 ** 20)', setup=setup, number=10) 24.570796012878418 >>> setup = """ def join_list(limit): return ''.join([`num` for num in xrange(limit)]) """ >>> timeit(stmt='join_list(2 ** 20)', setup=setup, number=10) 0.9801981449127197. More details