#!/usr/bin/perl -w
use strict;
use Benchmark 'cmpthese';

our $s = "HELLOWORLD" x 1024;
cmpthese(1_000_000, {
                     'slash_i' => sub { $s =~ m/hello/i; $s =~ m/jello/i },
                     'brackets' => sub { $s =~ m/[Hh][Ee][Ll][Ll][Oo]/;
                                         $s =~ m/[Jj][Ee][Ll][Ll][Oo]/; },
                    });