If you suspect that your applications are leaking, I suggest you use Devel::Leak or Devel::Leak::Object to detect where the leakage is, and then Devel::Cycle to see where the circular references in the leaking variables/objects are.

Here's a blogpost about detecting a leakage with these tools and fixing it by jrockway, and here's a bug report that I filed detecting a leakage in a module, also using these modules.

If the circular references are there by design, they should be weakened, as pointed by eye.