If you're running this on Apache, it gives you the option of running mod_perl. This gives you the benifit of having an interpreter built into the server, thus getting an enormous speed increase. AFAIK, neither Python or Ruby have such an advantage. PHP also has a built-in interpreter (mod_php), but mod_perl also offers hooks into the Apache API,

Even the most cursory peek into the world beyond Perl would have revealed to you that both mod_python and mod_ruby have been in existence for years, and allow hooking into the Apache API.