Book:OTRS 3.0 - Admin Manual/Chapter 21/3

Of course you should use mod_perl 2.0 ( http://perl.apache.org/ ). It's much faster (~ * 100) than pure cgi. But it needs more RAM.

Pre-established database connections
You can have the database connections pre-established on startup of the web server. This saves time (see README.webserver).

Preloaded modules - startup.pl
Use the startup script scripts/apache2-perl-startup.pl for preloaded/precompiled Perl modules on your mod_perl webserver to be faster, with a smaller memory footprint (see README.webserver).

Reload Perl modules when updated on disk
By default Apachee::Reload is used in scripts/apache2-httpd.include.conf. Disable it and you will get 8% more speed. But remember to restart the web server if you install any modules via the OTRS Package Manager, or any values in your SysConfig or in Kernel/Config.pm. Important: this would also mean you can't use the OTRS Package Manager via the web interface, you need to use the command line variant - bin/otrs.PackageManager.pl.

Choosing the Right Strategy
If you have a really large installation, say over 1,000 new tickets per 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 ).

mod_gzip/mod_deflate
If your bandwidth is small, use mod_deflate for Apache2. If you have an html page with 45k, mod_gzip/mod_deflate compresses it to about 7k. The drawback is that this increases the load on the server side.