I have an AIX 5.2 (16 GB RAM), Apache 2.2.8, MySQL 5.0.51a and mod_per
2.04 environment.  I had a Perl cgi-bin program using CGI.pm that I
converted to work in mod_perl.  The converted script still uses CGI.pm
and is now enabled in Apache via:

PerlModule ModPerl::Registry
Alias /perl/ /usr/local/apache2/perl/
<Location /perl/> 
    SetHandler perl-script
    PerlResponseHandler ModPerl::Registry
    PerlOptions +ParseHeaders
    Options +ExecCGI
    Order allow,deny
    Allow from all
</Location> 

I have my startup.pl containing:

use Apache::DBI;
use DBI();

Called in httpd.conf with:

PerlPostConfigRequire  /usr/local/apache2/scripts/startup.pl

Apache was compiled with --with-mpm=prefork

All webpages are accessed using SSL.  I am investigating offloading SSL,
but that will take a few months to accomplish.

If only a few users are using the application then performance is fine.
By this I mean the display of a MySQL query to a webpage takes a few
seconds.  Once we get over 20 users performance degrades to about 45
seconds.

Any tips would be appreciated.