Here's the code:

use Benchmark 'cmpthese';
use Regexp::Keep;
my $s = "abc.def.ghi.jkl";
cmpthese(-5, {
  japhy => sub { (my $x = $s) =~ s/.*\K\..*// },
  old   => sub { (my $x = $s) =~ s/(.*)\..*/$1/ },
});
[download]

In 5.6.1:

old   = 40280.54/s
japhy = 74338.79/s
[download]

And with 5.8.0 (using the module, NOT my patch):

old   =  58188.18/s
japhy = 102409.25/s
[download]

So there's an appreciable speed-up.

_____________________________________________________
Jeff[japhy]Pinyan: Perl, regex, and perl hacker, who'd like a job (NYC-area)
s++=END;++y(;-P)}y js++=;shajsj<++y(p-q)}?print:??;