Use
CGI or
DBI (or both) built-in cacheing techniques. Basically, all you do is specify the module to use cacheing and it will do it automatically. This will NOT dramatically increase the number of users able to connect to the database but will certainly help to speed things up and take care of repeated queries (to its best extent). Some options i the modules are also available for tweaking. i hope you're using
mod_perl or
fastcgi!