Does Perl do something funny if you mess with the upper limit on a for-loop? It would seem that the code "wit" below would run faster (by 2) since it does half the loops, but it runs longer! Here's my code and output: 
use Benchmark
Benchmark::cmpthese( -10, {
  non => sub{my $g = 10; my $lim = 10;
             for ( my $i = 1; $i < $lim; ++$i ) { --$g }},
  wit => sub{my $g = 10; my $lim = 10;
             for ( my $i = 1; $i < $lim; ++$i ) { --$lim }}
} )

__END__

        Rate  non  wit
non 507747/s   -- -26%
wit 685879/s  35%   --

[download]

In reply to for limit by Anonymous Monk

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.