First there should be some basic learning of Perl and generally available related things. You should be able to relate a specific skill for specific purpose. Once you have these co-relation in mind practiced, you won't need to remember everytime. The sense of the purpose will make the learning clear and you will continue finding better way to do it. I would call that building a personal expert system.
in reply to Things every perl programmer should know?
In this specific example, you were looking for speed. Many other criteria can be applied for better performance at various stages.