I have noticed that Facebook works more smoothly in Chrome 10.0.x (the version which I have) than in FireFox 3.6. Some elements of Facebook like Add Friend Dialogue Box make FireFox hang for a little time and specially when facebook opens the "Suggest Friends" dialogue box it just hangs the whole firefox browser until it has fully loaded and all other tabs get in-accessible during this loading and execution and on the same computer I used Chrome and it just works fine; it renders the box smoother, faster and doesn't hang other tabs. In the meanwhile other tabs just keep working as normal.
Did you see the same problem? Please let me know your thoughts. :D Not sure how Fire Fox 4 will perform in this regard. I'll post my thoughts when I use Fire Fox.