At first, I was confused. I ran your script as given and produced similar results. Then, I changed your benchmark slightly and got different results. 

use strict;
use warnings;
use Benchmark qw(cmpthese);

my $string = '0' x 13;
cmpthese(
    0,
    {
        'eq_loop_string' => q{
            for ( 0 .. 12 ) {
                next if ( $string eq '0000000000000' );
                $_ = ( $string =~ tr/1/1/ );
            }
        },
        'eq_loop_sub' => sub{
            for ( 0 .. 12 ) {
                next if ( $string eq '0000000000000' );
                $_ = ( $string =~ tr/1/1/ );
            }
        },

        'tr_loop_string' => q{
            for ( 0 .. 12 ) {
                next unless ( $_ = ( $string =~ tr/1/1/ ) );
            }
        },
        'tr_loop_sub' => sub{
            for ( 0 .. 12 ) {
                next unless ( $_ = ( $string =~ tr/1/1/ ) );
            }
        },
        'eq' => q($string eq '0000000000000';),
        'tr' => q($string =~ tr/1/1/;),
    }
);

[download]
And now the results: 
                    Rate eq_loop_string tr_loop_sub tr_loop_string eq_loop_sub   tr   eq
eq_loop_string  124852/s             --         -8%           -15%        -38% -97% -98%
tr_loop_sub     136139/s             9%          --            -7%        -32% -97% -98%
tr_loop_string  147082/s            18%          8%             --        -27% -97% -98%
eq_loop_sub     200481/s            61%         47%            36%          -- -95% -97%
tr             4356550/s          3389%       3100%          2862%       2073%   -- -42%
eq             7530073/s          5931%       5431%          5020%       3656%  73%   --
Is it possible that perl was having to eval the strings each time the sub was called, thus skewing the results?

thor

Feel the white light, the light within
Be your own disciple, fan the sparks of will
For all of us waiting, your kingdom will come

In reply to Re: tr faster than eq? by thor
in thread tr faster than eq? by Keystroke

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