Benchmark: timing 5000000 iterations of regex1, regex2, split...
    regex1:  3 wallclock secs ( 4.38 usr +  0.00 sys =  4.38 CPU) @ 1142334.93/s (n=5000000)
    regex2:  3 wallclock secs ( 3.50 usr +  0.00 sys =  3.50 CPU) @ 1426940.64/s (n=5000000)
     split: 15 wallclock secs (15.07 usr +  0.00 sys = 15.07 CPU) @ 331762.99/s (n=5000000)