I don't know if it has anything to do with memory consumption but Perl 5.8.1. introduced a randomization of the order of the hash-elements from one run to the next. So something did change in the hash-code!
CountZero
"If you have four groups working on a compiler, you'll get a 4-pass compiler." - Conway's Law
Comment on Re: *solved* Hash Memory Usage Changes in 5.8.x?