use strict;
use Benchmark qw(cmpthese);

local $/ = undef;
open IN, "romeo-and-juliet-500-times.txt";
my $text = <IN>;
close IN;

# Ten iterations is enough with a 70 MB string!
cmpthese(10, {
  'i'       => sub { $text =~ /abc/ig },
  'chars'   => sub { $text =~ /[Aa][Bb][Cc]/g },
});

##</code><code>##

Benchmark: timing 10 iterations of chars, i...
     chars: 40 wallclock secs (38.37 usr +  0.04 sys = 38.41 CPU) @  0.26/s (n=10)
         i: 12 wallclock secs (11.43 usr +  0.01 sys = 11.44 CPU) @  0.87/s (n=10)
      s/iter chars     i
chars   3.84    --  -70%
i       1.14  236%    --