There have been several posts about the fact that LW does NOT work with the Java developers preview 1.4.1. If you install it and LW continues to work it is simply because you haven't switched your Java to the new version but merely installed it.

I run LW on 10.2.2 (previously on 10.1.x as well) without any noticeable slowdown. I would ask how much memory you have on your machines because if LW is taking a large amount of CPU it is possible it is thrashing trying to swap in memory. I am running with 512 meg. You can use process viewer to determine how much cpu and memory LW is taking. The critical number is the resident memory size as this is the number of physical pages you actually are using.