Someone should make this a sticky. As discussed at length in this thread a few days back downgrading from Java 1.5.x to JRE 1.4.2 does the trick. Limewire starts at rocket speed for me now.

People may argue till kingdom come about how good the improvements in Java 1.5 are, but if it doesn't perform, well it has to stand in line as far as I'm concerned.

Hope this helps someone.