To question your assessment I tested it on my own machine: python3 -m timeit -s 'x = 8' 'x in range(1000)' 1000000 loops, best of 3: 0.405 usec per loop

To question your assessment I tested it on my own machine: python3 -m timeit -s 'x = 8' 'x in range(1000)' 1000000 loops, best of 3: 0.405 usec per loop python3 -m timeit -s 'x = 8' '0 <= x < 1000' 10000000 loops, best of 3: 0.0742 usec per loop python3 -m timeit -s 'x = 8' 'x in range(100000)' 1000000 loops, best of 3: 0.405 usec per loop python3 -m timeit -s 'x = 1123' 'x in range(100000)' 1000000 loops, best of 3: 0.415 usec per loop python3 -m timeit -s 'x = 1123' '0 <= x < 100000' 10000000 loops, best of 3: 0.0745 usec per loop While 0<=x<10 seems to be 5 times faster, both seem to be independent of the actual chosen values.