Perl qr// op speed.

gistfile1.pl

$ cat qr_speed.pl 
use strict;
use Benchmark qw/ cmpthese /;

my $re_string = 'a.c';
my $re_regexp = qr/a.c/;

sub match {
	my $re = shift;
	"abc" =~ /$re/;
}

cmpthese(1_000_000, {
	string => sub { match($re_string) },
	regexp => sub { match($re_regexp) },
});


$ perlbrew exec perl qr_speed.pl 
perl-5.10.1
==========
            Rate regexp string
regexp 1086957/s     --   -45%
string 1960784/s    80%     --


perl-5.12.4
==========
            Rate regexp string
regexp 1176471/s     --   -38%
string 1886792/s    60%     --


perl-5.14.2
==========
            Rate regexp string
regexp 1136364/s     --   -51%
string 2325581/s   105%     --


perl-5.16.0
==========
            Rate regexp string
regexp 1063830/s     --   -50%
string 2127660/s   100%     --


perl-5.17.0
==========
            Rate regexp string
regexp 1030928/s     --   -44%
string 1851852/s    80%     --


perl-5.8.9
==========
            Rate regexp string
regexp 2173913/s     --    -0%
string 2173913/s     0%     --