Firefox 5 arrives early -- get it now!
It's not officially released until tomorrow, but if you'd like to have an early look at Firefox 5 then the final build is actually available now, and while the "new features" list is a little on the short side, the browser includes some interesting tweaks which are well worth having. Mozilla posted the release candidate just three days ago.
You won't find these by examining the interface, though. The only notable visual change is that the Do Not Track privacy feature introduced in Firefox 4, which has been relocated so it's easier to spot (top of the Tools > Options > Privacy dialog, where it really should have been in the first place), otherwise you might just as think you're using Firefox 4.
Web development tweaks are in unusually short supply, too. There's support for CSS animations, a technology that makes it easy for developers to create simple web animations, even if they don't know JavaScript. But while the 5.0 beta release notes talked about "improved standards support for HTML5, XHR, MathML, SMIL, and canvas", how noticeable these will be is still open to question: we ran Firefox 4.01 and 5.0 at HTML5test.com and they both returned identical scores.
What seems much more interesting to us were the promised improvements in memory and networking performance. Would these deliver anything visible to the end user? We ran a few tests on a Windows 7 system, with some encouraging results.
We found initial memory use (private working set), for instance, dropped from 125 to 93MB. Resource use also fell, sometimes significantly -- so, for example, threads dropped from 54 to 40. And maybe as a by-product of these efficiencies, launch speed improved by up to 20 percent. Mozilla posted the release candidate just three days ago.
Was this just a one-off launch time benefit, though? To check this, we opened five additional tabs, and found even greater improvement in RAM and resource use. This suggests individual tabs are now also more efficient, so you should be able to open even more of them before running into any performance or stability issues.
Just in case that's not enough, Firefox 5 also now makes more intelligent use of its persistent HTTP connections. For the most part, this is just as uninteresting as it sounds, but HttpWatch ran some benchmarks that show dramatic improvements in a few situations, with, for example, a test screen image loading twice as fast thanks to the new feature.
Forget the lack of visible changes, then. Firefox 5 does have several interesting additions under the hood. Go grab a copy for yourself and see what these performance tweaks can do for you.