well, after reading how internaly Perl solves memory management problems I realised that its extremely fast and there is no need to do anything unless you have to. Perl interpreter have some extremly smart algorithms. For example, Perl does not imediately deletes some data in memory, what it does is marking the memory and variables which will not be used anymore. All variables are linked like in linked lists or trees and when some variable is no longer needed the pointer of previous one points to the variable after the one that is no longer needed. Like that, there is no time consumpion and the process which really deletes those un-needed variable will see that the variable is marked and will alter the pointers.