I’ve been using beta 3 a little bit at work and have noticed some performance enhancements and the infamous Firefox memory hogging issues seems to be a little more under control. The general feedback on the web so far is that beta 4 sucks less than beta 3 which is good news right?
In my own early testing, the most significant improvements here are in performance; I’m seeing both memory and CPU load lowered from beta 3, and I’ve not yet had beta 4 spike to 100% CPU (which was frequent for me with beta 3). Other changes include full-page zooming (which zooms graphics as well as text), a better algorithm to help guess what you’re typing into the address bar, and more native look and feel on all platforms. There are still some significant bugs (in areas such as MathML, displaying GMail, and difficulties with WMP), but overall, Firefox 3 is a big improvement over version 2 even at this point in its lifecycle. (via web worker daily)