I have been using nightly builds for months and must say the Rc1 is a horrible step backwards. Nightly build 4b6pre20110305 is so fast and stable compared to RC1 and 4.1alphas that I REALLY wonder what happened in the last 10 days. Esp when trying to scroll on zoomed pages RC1 and later often freeze for several seconds up to a minute.
In 4b6pre this does not happen at all. If they make Rc1 the final they will face a lot of justified flak.
I will stick with 4.0b6pre-20110305 until this issue is fixed.