Benchmark: timing 1000000 iterations of regexp1, regexp2, regexp3, replace, split, substr...
   regexp1: 26 wallclock secs (20.06 usr +  0.06 sys = 20.12 CPU)
   regexp2: 25 wallclock secs (20.02 usr +  0.06 sys = 20.08 CPU)
   regexp3: 17 wallclock secs (14.83 usr +  0.04 sys = 14.87 CPU)
   replace: 17 wallclock secs (13.05 usr +  0.03 sys = 13.08 CPU)
     split: 30 wallclock secs (24.56 usr +  0.09 sys = 24.65 CPU)
    substr: 11 wallclock secs ( 8.46 usr +  0.02 sys =  8.48 CPU)