There's the odd chance you're connected thru a dud or poor performing ultrapeer. You can close LW & reconnect to see if it picks up on newer ones. Check the addresses of the UP's on the connections window before you close LW.

If that doesn't help, perhaps try deleting your LW Preferences folder whilst LW is closed; instructions here: Point #2 & 3 in Fixes for Limewire (sample image included at bottom of page.) But if you do this you will need to reset all your options such as connection speed, downld location, etc. next time you open LW.