Obviously efficency is important, but if a concern is about your script hogging the CPU when its running, have you considered a non-perl solution? Namely, lower the priority of the process running. It won't run faster, but at least other processes won't be impacted as much by your script. Go to the command line and type: start /? for info on how to start w/ a lower priority. Note, most things start with NORMAL, so using /LOW or /BELOWNORMAL should give your other processes some breathing room.

-jbWare