I'm not sure I understand what you are trying to show. I currently have a much larger sample of what I wrote. And it quite happily chews up memory with a full queue (more than 0). The queue always shows the correct size but for some reason it keeps eating more memory.

The queue you have here would show the same problem I have when I analyze it under Devel::Leak I still see it allocating extra scalars every time it dequeues.

Point being, my little piece of code does what my poor brain says will be just of few megs of ram. But instead it takes 80+.