Homescreen scrolling, it hard to say since there are 2 right now that kills any other launcher. Some ppl complained about 2.1 or the Droid being slow, I think they just needed better launchers.
FWIW, after letting the phone calm down after first boot/reboot, the scrolling is better than stock 2.1 But, is that cuz of Froyo or is it cuz of a better stock launcher? Testing scrolling in the settings might give a better indicator of any improvements. But, u have to let the phone finish whatever background things its doing.
One thing I did noticed about improvements with Froyo, when running Quadrant on 2.1 at 1Ghz, the CPU test always hung on 11/12 for around 1 minute, maybe a lil less. On Froyo, on 800Mhz, the CPU test doesnt hang. ALL the test just fly by now.