The update isn't as extraordinary as some may think. I updated early, several hours after it's release on Samsung Kies Mini. First thing I did was run a Quadrant score before even importing contacts from my G services. The score was less than impressive. I ran daily test on my rooted 2.1 with OCLF2.0 running with scores peaking at 2500. The 750(something) that I got from the Froyo update was less than impressive.
I have since rooted using SuperOneClick since Z4Root method doesn't work on the Froyo build. I have also tried the OCLF 2.0 which failed, but then it ran faster. Not really sure if the LagFix worked, and it's currently telling me I cannot un-do LagFix or retry.
Either way, Froyo build isn't that impressive as far as speed. However, I haven't noticed any lag issues at all after rooting and running (maybe) the lagfix.