~$ perl vert4.pl
Benchmark: timing 3 iterations of 1, 10, 100, 1000, 10000, 100000, 1000000...
         1:  1 wallclock secs ( 0.94 usr +  0.01 sys =  0.95 CPU) @  3.16/s (n=3)
            (warning: too few iterations for a reliable count)
        10:  1 wallclock secs ( 0.23 usr +  0.02 sys =  0.25 CPU) @ 12.00/s (n=3)
            (warning: too few iterations for a reliable count)
       100:  0 wallclock secs ( 0.17 usr +  0.01 sys =  0.18 CPU) @ 16.67/s (n=3)
            (warning: too few iterations for a reliable count)
      1000:  0 wallclock secs ( 0.16 usr +  0.03 sys =  0.19 CPU) @ 15.79/s (n=3)
            (warning: too few iterations for a reliable count)
     10000:  0 wallclock secs ( 0.18 usr +  0.00 sys =  0.18 CPU) @ 16.67/s (n=3)
            (warning: too few iterations for a reliable count)
    100000:  0 wallclock secs ( 0.20 usr +  0.03 sys =  0.23 CPU) @ 13.04/s (n=3)
            (warning: too few iterations for a reliable count)
   1000000:  1 wallclock secs ( 0.23 usr +  0.03 sys =  0.26 CPU) @ 11.54/s (n=3)
            (warning: too few iterations for a reliable count)