I just got my Hardy update for Firefox 3.0b4, and the speedup leaves me speechless.
I am on 100mbit internet so most of my web browsing delays are in rendering time, and this release just makes Firefox FLY and feel like Safari or Opera, even better in many cases (i.e. heavy table sites)
I am right now merging my Firefox 3.0 beta3 packaging with the beta4 packaging in Hardy to generate some backports. Expect about 1 week total time between now and the availability of official firefox 3 beta 4 backports