memo

This is perl, v5.8.8 built for i386-linux

#!/usr/bin/perl 

use strict;
use warnings;
use Benchmark qw(:all);

cmpthese( -2 , {
    hatena => sub {
        my $str = 'hogehoge2r';
        $str =~ s/(?:2r|3|3r)$//;
    },
    nohatena => sub {
        my $str = 'hogehoge2r';
        $str =~ s/(2r|3|3r)$//;
    },
    ushironihatena => sub {
        my $str = 'hogehoge2r';
        $str =~ s/(2r|3r?)$//;
    }
    });

hatena          514864/s             --           -57%           -61%
nohatena       1190866/s           131%             --            -9%
ushironihatena 1310720/s           155%            10%             --