You'll have to Benchmark it yourself to see if it's any faster, but maybe:

c:\@Work\Perl\monks>perl -wMstrict -le
"$_ = 'iiiiiiiiMMMMMMMMMMMooooooooooooMMMMMMMMMMiiiiiMMMMMMMMoooo';
 my $count =()= $_ =~ m{ M+ }xmsg;
 print $count;
"
3
[download]