I'll be following this thread with interest as I'm seeing similar behaviour on my FreeBSD box. I also have a local server on OSX. My Apache children are around 20MB of OSX and 75MB on FreeBSD. This is using top to measure.
I'm also getting an awful lot of seg faults in the log but I haven't isolated that to perl yet and the server comes with mod_php installed as well. Which I have got to get rid of. My Perl code is 2MB in total (37 packages). I have still got a *lot* to learn about how mod_perl loads things and allocates them into ram but I'll not hijack this thread with that. Any pointers to manuals greatly appreciated. I'm also running prefork. I'll look into finding out how Apache::Status can tell me what's loaded. Hoping to be able to confirm your findings here.