Of course you should use mod_perl ( http://perl.apache.org/). It's much faster (~ * 100) than pure cgi. But needs more RAM. So your httpd with mod_perl will be about 16 MB (~10MB shared).
You can have the datababase connections being established on process startup (httpd). This saves also time (see README.webserver).
Use the scripts/apache-perl-startup.pl startup script for preloaded/precompiled perl modules on your mod_perl webserver to be faster and smaller (see README.webserver).
Per default Apache::StatINC (mod_perl1) or Apache::Reload (mod_perl2) is used in scripts/apache-httpd.include.conf. Disable it and you will get 8 % more speed. But remember to restart the webserver if you change the Kernel/Config.pm or any other modules!
If you have a really large installation (over 1000 new tickets a day and over 40 Agents) it is a good idea to read "Choosing the Right Strategy" (http://perl.apache.org/docs/1.0/guide/strategy.html).
Anyway, if your bandwidth is a little bit small use mod_gzip (http://www.schroepl.net/projekte/mod_gzip/). If you have a html page with 45k, mod_gzip compresses it. The page will be about 7k. That's really nice.
If you want to block http DoS (Denail of Service) attacks, use mod_dosevasive. (http://www.nuclearelephant.com/projects/dosevasive/).