Actually, you and I are both correct. ;-) What I forgot was that the time I benchmarked it, it was under NT. I just did a benchmark on NT and Linux and got the following results:

NT:
Time::HiRes::time() - timethis 600000: 20 wallclock secs (19.99 usr + 0.00 sys= 19.99 CPU) @ 30015.01/s (n=600000)
time() - timethis 600000: 67 wallclock secs (66.73 usr + 0.00 sys = 66.73 CPU) @ 8991.46/s (n=600000)

Linux:
Time::HiRes::time() - timethis 600000: 3 wallclock secs ( 1.22 usr + 0.24 sys = 1.46 CPU)
time() - timethis 600000: 1 wallclock secs ( 0.27 usr + 0.17 sys = 0.44 CPU)

Anyway, enough of the thread hijacking.

The modulo operator is a great idea, good suggestion.