A question for you,
ceedee.
Do these scripts use strict and warnings? If they don't, it would be a good idea to make them do so. This will considerably simplify your maintenance task in future.
See my node Thoughts on revisiting old code.
Secondly, a profiler such as Devel::DProf can help with your subroutines and %INC. You might also consider Devel::SmallProf which gives execution times and counts of each line of code. BTW you don't want the profiler turned on normally, as it considerably slows down execution of the scripts.