Admittedly, it would be interesting to see how the benchmark goes with different data sets...
I used the following text, not big but should be enough 
my $s = 'Lorem ipsum dolor sit amet, consectetuer adipiscing elit,
sed diam nonummy nibh euismod tincidunt ut laoreet dolore magna
aliquam erat volutpat. Ut wisi enim ad minim veniam, quis nostrud
exerci tation ullamcorper suscipit lobortis nisl ut aliquip ex ea
commodo consequat. Duis autem vel eum iriure dolor in hendrerit in
vulputate velit esse molestie consequat, vel illum dolore eu feugiat
nulla facilisis at vero eros et accumsan et iusto odio dignissim qui
blandit praesent luptatum zzril delenit augue duis dolore te feugait
nulla facilisi.';
$s = s/[\r\n]//g;

[download]
After reading the code of ikegami and lodin, "I personally believe"d they were faster but i was wrong: 
        s/iter ikegami   lodin     oha
ikegami   1.43      --     -1%    -48%
lodin     1.42      1%      --    -48%
oha      0.740     93%     92%      --

[download]
I suspect the regex engine is so much smarter in finding fixed char repetition to gain more then the gain of doing lots regex call...

Oha

PS: i didn't passed the string to the subs and didn't returned the results.

Update: removed the \n from the string, updated results

Update: my code is broken: it must reset pos to the previous pos+1 (if not some subpatterns aren't matched). updated results are as "i personally believe"d: 

        s/iter     oha   lodin ikegami
oha       1.66      --    -12%    -14%
lodin     1.46     14%      --     -2%
ikegami   1.43     16%      2%      --

[download]

In reply to Re^5: how to count the number of repeats in a string (really!) by oha
in thread how to count the number of repeats in a string (really!) by blazar

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