There's also a wrong answer (Unix variant):

locate perl | grep -i ModuleCategory/ModuleName, maybe with a grep for 'pm$' added. If necessary, replace locate ... with find /usr/*/perl* /opt/perl* /usr/*/*/perl*, but that's a bit slower.

It misses some, it adds some, but if you rarely use the 'correct' methods (@INC as mentioned above or the FAQs), it's way faster to remember :). So don't forget about the lowtech approach.