Benchmark: timing 100000 iterations...
One Big Regexp:  7 wallclock secs (6.22 CPU) @ 16077.17/s (n=100000)
Several Regexp: 12 wallclock secs (11.27 CPU) @ 8873.11/s (n=100000)
With index(): 11 wallclock secs (8.71 CPU) @ 11481.06/s (n=100000)