Yeah Java is not the most efficient. WHich java do you have now? SOmetimes 1.4.2 or 1.5 does better for some than others. It seems to depend on their set up. You could also try deleting your LW prefrences folder whilst LW is closed; instructions: Fixes for Limewire

Also get rid of some of your incomplete files if you have a lot. Go to downlds window & click at top of Progress bar so it arranges them by % then delete all those at 0%. Then go to your incomplete folder & arrange it by size view & delete all those at 0 KB. (BUT don't delete your downloads.dat file!)