If you are using END just to free the memory you don't need because after call END (in a normal Perl process) we have the global destruction, where everything will be destroied and cleaned.

The usage of end is only needed if you need to make some operations like save things to a file, unlock DB tables, etc... So, is only needed for things that will still exists after the process be dead, in other words, only metters for things outside of your process.