Firefox 4 Beta 9 is of course faster than its previous self, Firefox 3.6. Based on Mozilla's Kraken benchmark test, it's 2.5x faster.
It's faster to start up and better at handling animations, through the implementation of compartmentalized garbage collection.
It brings with it a Chrome-like viewing area for tabs called Panorama. Whereas Chrome shows the tabs of Web sites most frequently accessed, Firefox Panorama displays the tabs that are currently open and allows those tabs to be grouped, which may provide better access to multiple sets of tabs when many tabs are open.
The latest beta includes an overhaul of the browser's history and bookmarking code, resulting in better performance. Many of the changes in Beta 9 represent bug fixes and are too geeky to detail in polite company. Lovers of code can find the laundry list here.
Perhaps oblivious to the ways in which his choice of words could be hijacked for ridicule -- never call your product a pile of any sort -- Firefox director of product platform management Chris Blizzard calls Beta 9 "a huge pile of awesome." More notable than Blizzard's phrasing is his list of developer-oriented enhancements to Firefox.
Having witnessed the popularity of Google's rival Chrome browser, Mozilla appears to be making a concerted effort to position Firefox 4 as the preferred choice for Web development. New DOM functionality, CSS capabilities, and security tools will certainly appeal to Web application creators.
Blizzard also happened to mention Firefox 4's support for WebM. Google made waves earlier this week by siding with Mozilla and declaring its intent to drop support for H.264 video.
Mike Shaver, VP of engineering at Mozilla, praised Google's announcement, demonstrating that even though Firefox and Chrome compete, open source organizations have some common interests.