Antoine: I agree that it does look weird to have thousands separators at one place and not at the other but IMO it's still slightly better - the number formatted with separators is simply more readable that separator-less one.

R. David Murray: what's the acceptable separator then? Modifying it to be locale-aware would make it inconsistent with the rest of the output (which, admittedly, is also the case with introducing space separator, dot still is the fraction separator though).

I modified my patch to not have the separators at all, please find timeit-v3-actual-changes-no-separators.patch - if that's the condition for accepting this patch then so be it - the description of the patch would be "print number of loops per second" and the example output is:

10000 loops, best of 3: 34.6 usec per loop (28870 loops/s)