use Benchmark qw(:all);

my $str = 'iiiiiiiiMMMMMMMMMMMooooooooooooMMMMMMMMMMiiiiiMMMMMMMMoooo';

my $these = {
    'count' => sub {
        my $count = 0;
        $count++ while $str =~ /(M+)/g;
        $count;
    },
    'regex' => sub {
        my $count = () = $str =~ /(M+)/g;
    },
    'split' => sub {
        $#{[split /M+/, $str, -1]};
    },
};

printf "%-10s %d\n", $_, $these->{$_}->() for sort keys %$these;
print "\n";

cmpthese(-1, $these);