This video here shows how "well" fennect runs on N900.
http://www.youtube.com/watch?v=Ih5SrhCJukI

Basically the performance is crap. Nowadays I (and users who are accustomed to for example iphone) expect smooth scrolling... maybe 30fps is still acceptable, but that can't be claimed good anymore.

Ok, as a disclaimer, it's still youtube, so maybe I would give it a chance, but if the performance is similar than on that video, then out it goes.
Phones own browser works much more smoothly (even on youtube)