Depending on the nature of your code (monolithic, subs, OO), you may find use in using Devel::Dprof to trace the execution time of your code and from there find out where you can optimize. You didn't say whether or not your program was a CGI, or standalone. Can you verify that the memory consumption issues are inside the perl, and not outside, such as calling external executables which leak memory and don't free() it back up?

Another one to try is Devel::Peek has a 'memory footprint debugging' API also. I haven't used either of these, but they look promising towards determining your issue of memory consumption.