Couple of months ago I complained about 3.1M6 performance here. Since then a lot of things have changed in Eclipse world. The final 3.1 release is about to go out next week.
I have been using 3.1RC3 for a week now and am quite happy with the performance. I have kept eclipse running continuously for the last 6 days and not once has it hanged, crashed or shown the white rectangle.
Congrats to the Eclipse team for the great work.