Actually I got something similar happening to me. At home I'm on DSL and when I launch LimeWire (4.10 Pro) it runs just fine (Turbo-charged) for about five minutes than gradually dropps speed all the way down to 1-2k per downloads, or even 0k. I have a maximum of 8 downloads running at once. The connection indicator on the lower left bottom also slowly drops down and about after 10 minutes it loses connection completely. Then it gets it back to about 'poor connection', but loses it again and on and on.

If I quit LimeWire at this point and relaunch it again, it always starts in turbo charged mode but the story starts all over. Few minutes and start slowing down finally drops out completely.

I don't run any other programs for testing purposes and I cleared out my library too so those won't effect performance. Basicaly it's a clean system that starts downloading a few files.

My system: G4 dual 533, OS X 10.3.9, 1 Gig ram, DSL 1.2 mbps.