For hobby purposes, I have a shared space on a hosting server that is providing, as many of them are, both PHP and Perl CGI. I have read on several places that CGI scripts
This is a fairly subjective issue for deciding what to use for a hobby. I decided to learn Perl as a hobby after looking into PHP and not liking the fact that I could not read most of the PHP out there and being daunted by the list of builtin functions.
The first few things I did were CGI scripts for contact forms and a photo album generator. I was on a cheapo shared hosting plan and I was not getting any performance problems so the performance issue never came into play.
Instead, the existence of comp.lang.perl.misc and CPAN ensured that I never reconsidered my decision not to delve into PHP.
In the mean time, I realized most of the content on my web sites is static once generated, so now I write Perl scripts to generate the content offline.
So, my answer is, pick a small project, anything will do, and implement it using Perl and appropriate CPAN modules and see if you like it.