gistfile1.txt

andreypopp> python -m timeit -v "range(40)[:len('string')]"                                                           ~
10 loops -> 1.41e-05 secs
100 loops -> 0.000143 secs
1000 loops -> 0.00119 secs
10000 loops -> 0.0117 secs
100000 loops -> 0.117 secs
1000000 loops -> 1.16 secs
raw times: 1.17 1.17 1.18
1000000 loops, best of 3: 1.17 usec per loop
andreypopp> python -m timeit -v "range(40)[:6]"                                                                       ~
10 loops -> 1.22e-05 secs
100 loops -> 0.000105 secs
1000 loops -> 0.00107 secs
10000 loops -> 0.0104 secs
100000 loops -> 0.105 secs
1000000 loops -> 1.03 secs
raw times: 1.04 1.03 1.04
1000000 loops, best of 3: 1.03 usec per loop