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.
You can have the database connections pre-established on startup of the web
server. This saves time (see README.webserver).
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).
By default Apache::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.
This would also mean you can't use the OTRS Package Manager via the web
interface, you will need to use the command line variant -
bin/otrs.PackageManager.pl.
If you have a larger installation, e.g. over 1,000 new tickets per day and over 40 agents, it is a good idea to read the chapters on Performance of the mod_perl User's Guide ( http://perl.apache.org/docs/2.0/user/index.html ).