It works well in that benchmark, but falls down here: 
use Benchmark qw(cmpthese);

my $str = "wwibblewibblewibblewibbleibblewibblewibblewibble";

cmpthese -1, {
    regex => sub {
        my %count;
        ++$count{$_} for $str =~ /(?=(..))/g;
    },
    substr => sub {
        my %count;
        ++$count{substr $str, $_, 2} for (0 .. length($str) - 2);
    },
    unpack => sub {
        my %count;
        my $n = length($str) - 1;
        ++$count{$_} for unpack qq{(a2 X)$n}, $str;
    },
};

          Rate  regex unpack substr
regex  15316/s     --   -43%   -74%
unpack 26935/s    76%     --   -54%
substr 58514/s   282%   117%     --

[download]
substr slows down 50% if the string contains utf-8 characters, but it's still significantly faster than unpack in this benchmark: 
my $str = "wwibblewibblewibblewibbleibblewibblewibblewibble\x{20ac}";

          Rate  regex unpack substr
regex  14222/s     --   -35%   -51%
unpack 21976/s    55%     --   -24%
substr 29020/s   104%    32%     --

[download]

In reply to Re^5: dice's coefficient by Anonymous Monk
in thread dice's coefficient by locked_user zanruka

Title:
Use:  <p> text here (a paragraph) </p>
and:  <code> code here </code>
to format your post, it's "PerlMonks-approved HTML":


  • Posts are HTML formatted. Put <p> </p> tags around your paragraphs. Put <code> </code> tags around your code and data!
  • Titles consisting of a single word are discouraged, and in most cases are disallowed outright.
  • Read Where should I post X? if you're not absolutely sure you're posting in the right place.
  • Please read these before you post! —
  • Posts may use any of the Perl Monks Approved HTML tags:
    a, abbr, b, big, blockquote, br, caption, center, col, colgroup, dd, del, details, div, dl, dt, em, font, h1, h2, h3, h4, h5, h6, hr, i, ins, li, ol, p, pre, readmore, small, span, spoiler, strike, strong, sub, summary, sup, table, tbody, td, tfoot, th, thead, tr, tt, u, ul, wbr
  • You may need to use entities for some characters, as follows. (Exception: Within code tags, you can put the characters literally.)
            For:     Use:
    & &amp;
    < &lt;
    > &gt;
    [ &#91;
    ] &#93;
  • Link using PerlMonks shortcuts! What shortcuts can I use for linking?
  • See Writeup Formatting Tips and other pages linked from there for more info.