Benchmark: running regex, substring for at least 2 CPU seconds...
     regex:  4 wallclock secs ( 2.72 usr +  0.01 sys =  2.73 CPU) @ 740317.95/s (n=2021068)
 substring:  2 wallclock secs ( 2.66 usr +  0.02 sys =  2.68 CPU) @ 17332.84/s (n=46452)
              Rate substring     regex
substring  17333/s        --      -98%
regex     740318/s     4171%        --