Firefox 8, which only just appeared on the Nightly channel, is already 20% faster than Firefox 5 in almost every metric: start up, session restore, first paint, JavaScript execution, and even 2D canvas and 3D WebGL rendering. The memory footprint of Firefox 7 (and thus 8) has also been drastically reduced, along with much-needed improvements to garbage collection.

According to our own benchmarks, start up, session restore, and first paint — how long it takes Firefox to appear after you click its icon, and how long it takes to re-open your previous tabs — have been continuously tackled since Firefox 7 first emerged, about two months ago. There’s a 10% difference between Firefox 5 and 7 — and a further 10% speed-up between FF7 and FF8. This isn’t merely an under-the-hood, synthetic-benchmark, on-paper thing either: the difference between FF5 and FF8 is very, very noticeable.

On the 2D canvas front, the huge 20% speed-up is due to the addition of a new graphics backend in Firefox 7 called Azure, which is a unified 2D graphics API that Firefox can use across every platform. At the moment, Cairo handles the interface between Firefox and the host OS’s 2D rendering libraries. Cairo’s performance on top of Direct2D (Windows 7/Vista) is excellent, but it’s not great on either XP or Mac OS X. Azure removes the Direct2D and Quartz (OS X) go-between and allows Firefox to write directly to the underlying 3D subsystems (Direct3D and OpenGL). At the moment, the performance gains are around 20% on Windows — but on OS X, the gains could be even higher. You can follow the Azure implementation on Bugzilla to keep up with the latest changes.

3D WebGL performance has also improved by around 20% between Firefox 5 and 8, but this won’t be because of Azure; it’s probably just the result of further tweaking to make WebGL less insecure and to ready-up for primetime. Finally, Firefox 8 is considerably faster at JavaScript execution, posting benchmark results that are about 15% faster than Firefox 5 (FF8 vs FF5).

While comparison with other browsers has become a little passe in recent months — they’re all so damn similar! — it’s worth noting that Firefox 8 is as fast or faster than the latest Dev Channel build of Chrome 14. Chrome’s WebGL implementation is still faster, but with Azure, Firefox’s 2D performance is actually better than Chrome. JavaScript performance is also virtually identical.

The only real difference now between Chrome and Firefox (and Internet Explorer 9) is the fancy, Googlesque speculative pre-resolution of DNS and pre-loading of websites. Mozilla can spend the next year improving Firefox’s rendering speeds, but the negotiation and downloading of websites is always going to be the slowest part of surfing the web — and that’s where Google Chrome truly excels. Firefox might be fast, but Chrome feels fast.

Download Firefox 8 (Nightly) or Firefox 7 (Aurora)

[Note: Firefox 6 is currently in Beta and will be the next stable build — and six weeks after that, Firefox 7 will follow. Read more about the Firefox release channels.]