3COM router, did you forward a port for it for LW?
Anyway, there's ways of reducing cpu use.
After opening LW, let it settle for at least 15 mins before doing anything. LW will be busy loading incompletes & shared files & simultaneously trying to connect with each one. Let it settle.
Close any windows you're not using (like turning the lights off in rooms you're not in - it saves power), eg: Connections, Monitor & Library windows. Set your downloads for Auto-clear. Delete search results that are a few hours old.
If you are running as an ultrapeer then this will use up more power. If you're not running as a UP then reduce your upload bandwidth to about 80% or less.
Don't use the Resume button on all your files. This will particularly slow down LW & possibly your computer. It may also affect LW's connection quality. The most effective way of finding sources is to manually search for them.
Personally I often turn LW on & leave it to end for itself. eg:
http://www.gnutellaforums.com/showth...028#post116028