#!/usr/bin/perl -w

use strict;
use Benchmark qw(:all);

my @rands = qw (A---B-B---B---D----F----G----H----J----K-----L---F-D--F---G--H---_R_-f-F-ff-----f
    ----F----G--
    ----F----G------F----G------F----G--
    ----F----G------F----G------F----G------F----G--
    ----F----G------F----G------F----G------F----G-----F----G---
    ----F----G-----F----G---
    ----F----G------F----G------F----G--);

my $max = @rands;

cmpthese(1000000, {
        'tr' => sub {
                $_ = $rands[int(rand($max))];
                my $x = tr/-//;
        },
        'm//' => sub {
                $_ = $rands[int(rand($max))];
                my $x = () = $_ =~ /-/g;
        },
        'for' => sub {
            $_ = $rands[int(rand($max))];
            my %cnt = ();
            my @chrs = split '', $_;
            foreach (@chrs) {
                $cnt{$_}++;
            }
            my $x = $cnt{'-'};
        },
    }
);
__END__
Benchmark: timing 1000000 iterations of for, m//, tr...
       for: 98 wallclock secs (95.68 usr +  0.09 sys = 95.77 CPU) @ 10441.68/s (n=1000000)
       m//: 55 wallclock secs (53.85 usr +  0.06 sys = 53.91 CPU) @ 18549.43/s (n=1000000)
        tr:  2 wallclock secs ( 1.81 usr +  0.00 sys =  1.81 CPU) @ 552486.19/s (n=1000000)
        Rate   for   m//    tr
for  10442/s    --  -44%  -98%
m//  18549/s   78%    --  -97%
tr  552486/s 5191% 2878%    --