Koopa 35
You mention the performance not being that fast but i think the Dalvik JIT compiler is something that you will really notice once devs recode their apps for the platform. It sets things up for future and means apps can get more performance out of the same hardware... like the game demo at Google I/O. Froyo from what i remembered wasnt touted as being mega fast though... the browser was, with the JIT good for application performance.
I also think the flash performance benefitted from the new tech...
they said froyo was 450% faster than 2.1 im not sure if it was from google or the writers ill check on that. but thats what was said. u know a lot more than me about compilers and things. i will be going back to iphone this june. ill keep my nexus one and test it out a few months down the lines to see if performance is better. as of now its crap.