perl-long-regex.pl

$ cat long-test.pl 
use strict;
use warnings;

use Benchmark;

# build a regex with a lot of alternations
my $r = '';
for my $l ('a'..'y', 'A'..'Y'){
        $r .= $l x 10;
        $r .= '|';
}
$r .= 'sanfrancisco\.com';


# build a long string
my $check_body = 'Z' x 14_000_000;
$check_body .= 'sanfrancisco.com';


# time them, with qr// and without
my $count = 1;
timethese($count, {
        without_qr => sub { testme( $r     ) },
        with_qr    => sub { testme( qr/$r/ ) },
});


sub testme {
        my $text_block_string = shift;
        if ($check_body =~ /($text_block_string)/ig) {
              print "match! $1\n";
        }else{
            print "no match :-( \n";
        }
        pos($check_body) = 0;
}

-------------------------------------------------------
$ perl long-test.pl 
Benchmark: timing 1 iterations of with_qr, without_qr...
match! sanfrancisco.com
   with_qr:  0 wallclock secs ( 0.01 usr +  0.00 sys =  0.01 CPU) @ 100.00/s (n=1)
            (warning: too few iterations for a reliable count)
match! sanfrancisco.com
without_qr: 15 wallclock secs (15.21 usr +  0.00 sys = 15.21 CPU) @  0.07/s (n=1)
            (warning: too few iterations for a reliable count)