Over in the land of Socialtext Open, we found that we were having big slowdowns because of $& somewhere in the code base. Turns out it was in Text::Balanced. I fired off mail to Damian and within half an hour he'd put out a new version that didn't use the evil variable.
If you don't know why $& is bad, see the docs for Devel::SawAmpersand. http://search.cpan.org/dist/Devel-SawAmpersand
