Before moving a script to Apache::Registry (or rewriting it as a mod_perl module) ask yourself: do all my Apache child processes need this? If the answer is yes, then go ahead; if not, leave it as a simple CGI.

Since Apache::Registry caches compiled scripts (well, it just leaves them compiled, more accurately) and mod_perl never releases compiled code (any more than a regular Perl interpreter does) anything you run either way is going to add memory for the life of the child it runs in. Occasional admin scripts, once-a-day statistics and that sort of thing should remain plain CGI for that reason.

..Theo