See also Re: Multiple Regex evaluations or one big one?

Also if you use

my $str1 = 
my $str2 = 
my $str3 = 
my $str4 =
my $str  = 'очень длинная строка ' x 10;
...

    'qr//i+m//' => q{ $str1 =~ /$re_i/; return; },
    'qr//+m//i' => q{ $str2 =~ /$re/i;  return; },
    'qr//+m//'  => q{ $str3 =~ /$re/;   return; },
    'qr'        => q{ $str4 =~ $re;   return; },
[download]

If you my $count = -3; you get Timing is consistently zero in estimation loop, cannot benchmark. N=134217728

What this means? don't worry about it :)

Hah, another old benchmark i had laying around

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

my @small = 1;
cmpthese( 500_000, {
    '__' => sub {
        for my $line ( @small ){
            next if $line !~ /\s+(-?\d+\.\d+)\s+(-?\d+\.\d+)/;
        }
        return;
    },
    '/_'.$].'_/' => eval '
        sub {
            for my $line ( @small ){
                next if $line !~ /'.
                qr{\s+(-?\d+\.\d+)\s+(-?\d+\.\d+)} # 5.12.2 (?-xism:
                                                   # 5.14.1 (?^:
                .'/;
            }
            return;
        }
    ',
    'qr' => sub {
        my $re = qr{\s+(-?\d+\.\d+)\s+(-?\d+\.\d+)};
        for my $line ( @small ){
            next if $line !~ $re;
        }
        return;
    },
    '/qr/' => sub {
        my $re = qr{\s+(-?\d+\.\d+)\s+(-?\d+\.\d+)};
        for my $line ( @small ){
            next if $line !~ /$re/;
        }
        return;
    },
## 2014-02-21-11:33:11
    'qr,//o' => do {
        our $gre = qr{\s+(-?\d+\.\d+)\s+(-?\d+\.\d+)};
        sub {
            for my $line ( @small ){
                next if $line !~ /$gre/;
            }
            return;
        };
    },
});

__END__
                 Rate        /qr/          qr     qr,//o         __ /_
+5.016001_/
/qr/         198807/s          --         -0%       -48%       -71%   
+      -75%
qr           198807/s          0%          --       -48%       -71%   
+      -75%
qr,//o       385505/s         94%         94%         --       -43%   
+      -52%
__           680272/s        242%        242%        76%         --   
+      -15%
/_5.016001_/ 800000/s        302%        302%       108%        18%   
+        --
[download]