This depends on what your children are doing, and what their memory usage patterns are. Perl does garbage collect, but it does so within a memory arena that grows but never shrinks. You might find that you need to kill and re-spawn your child processes just to be resource friendly.

This problem appears in a number of different forms, and many words have been written on how to write servers that pre-spawn (and recycle) their children. The Perl Cookbook devotes part of a chapter to it, and merlyn has written several Web Techniques articles that cover that ground.