From Doug MacEachern:
Mod_Perl for Linux brings together the full power of the Perl programming language and the Apache HTTP server. You can use Perl to manage Apache, and can respond to requests for web pages. Mod_perl gives you a persistent Perl interpreter embedded in your web server. This lets you avoid the overhead of starting an external interpreter and avoids the penalty of Perl start-up time, giving you super-fast dynamic content.