Mozilla answers WebKit with first mobile Firefox 4 beta
'We saved you from IE. And we will save you again'
Mozilla has released its first mobile Firefox 4 beta, offering test versions of the open source browser for both Google Android and Nokia Maemo.
"Early Firefox for Android builds were very slow compared to the stock browser," reads a blog post  from Mozilla man Matt Brubeck. "Performance is critical in a mobile browser, and our work in this area is starting to pay off. The new beta version is much speedier, and we have plans to make it even faster."
The beta also offers Firefox Sync, for syncing bookmarks, tabs, history, passwords, and form data across Firefox browsers on multiple devices. It handles those familiar Firefox add-ons. And it includes Mozilla's "Awesome bar", the address bar that suggests sites based on where you've surfed in the past.
Like the alpha version, the beta benefits from a split architecture known as Electrolysis, using one process for the user interface and one for rendering and running scripts. But unlike the alpha, it also incorporates Mozilla's new Layers architecture, designed to speed scrolling, zooming, and animation via hardware acceleration and other tweaks. Layers are shared between the UI process and the web content process, so that – at least in theory – the user can continue to scroll smoothly as pages are rendering.
Mozilla is also working on OpenGL hardware-accelerated compositing. But this is not yet available in the beta.
The Android incarnation of the browser requires at least version 2.0 of Google's OS, and it won't run on anything an ARMv7 processor, hooking into such hardware tools as the Thumb-2 instruction set and the NEON SIMD extension to speed performance. "With these optimisations it can't run at all on low-end hardware," Brubeck says. "For now, we're focusing on the current high-end phones, which will likely be next year's mainstream hardware."
The includes the Samsung Galaxy S – billed by Eric Schmidt as the iPhone's biggest rival – but Brubeck says Firefox JIT code regularly crashes on the Galaxy, and JIT is now disabled on the device. Mozilla suspects this is a kernel issue, saying that the MonoDroid JIT and Android's own Dalvik JIT show similar behavior. But Brubeck says the problem has been fixed in the Android 2.2 image for the Samsung Captivate that was recently leaked to the web, so a fix is expected on the Galaxy as well.
Brubeck bills mobile Firefox as a much-needed alternative to WebKit, the open source browser that serves as a basis for both the iPhone's Safari browser and the Android browser. "WebKit is an excellent project. But a growing number of mobile sites work only on WebKit. This is dangerously similar to the web 10 years ago, when Internet Explorer had an overwhelming market share and many sites used IE-specific markup. That made it hard for other browsers to compete, which killed the incentive for the dominant browser to keep improving," he says.
"We think people should have a meaningful choice of browsers on their current phones, just like they do on their computers. Increased choice will encourage all browsers to innovate and learn from each other, so that all of them improve faster."
You can download the mobile Firefox 4 beta here .
Since January, Mozilla has offered a stable Firefox browser for Maemo based on Firefox 3.6, but this was not available for Android. Firefox first hit Android when Mozilla released a pre-alpha  Fennec in April. ®