in reply to Program size and effeciency.
Your boss has to weigh the cost of a few more seconds of processor time versus the cost of paying you to rewrite the script, and then to debug what you wrote (a rewrite is going to introduce new, unexpected bugs).
Perl is about getting things done. While you may be itching to fix the code you've been charged with, it may not be cost effective to do so.
One of the biggest mistakes a programmer can make is to go and make a bunch of significant changes to something that's been working fine for a long time. Change may be warranted, but take the time to understand before jumping in to big changes.