Mozilla rolls out dev-only 64-bit Firefox for Windows

Long-delayed, fully 64-bit Windows version of Firefox emerges via Mozilla's special Developer Edition channel

Mozilla Firefox mug
Areta do Bem (CC BY 2.0)

Mozilla has revved its Developer Edition version of the Firefox to 38 and for the first time introduced a full 64-bit build of the browser for Windows.

Aside from matching Google, which has offered a 64-bit version of Chrome since last August, Mozilla's native 64-bit build of Firefox boasts three key features: faster execution speed, better security, and the ability to run larger programs.

An advantage of using 64-bit applications is their use of a larger address space on a server or desktop. For a browser like Firefox, this translates into having more tabs open at once and running more ambitious in-browser applications. But other advantages of 64-bit apps include better leveraging of address space layout randomization (ASLR), a common technique for protecting against software exploits. Mozilla touts this as a boon for 64-bit Firefox, and Chrome's 64-bit edition has similar functionality.

Firefox Developer Edition

Firefox Developer Edition, now in a 64-bit version, comes with a slew of tools specifically aimed at Web developers such as a built-in IDE for creating Firefox OS applications.

The third big boon for a 64-bit Firefox is increased execution speed for JavaScript -- specifically, JavaScript written using Mozilla's asm.js extensions, which allow highly optimized JavaScript to compile to code that runs close to the speed of native C. Mozilla has touted asm.js for porting C/C++ code to the Web, and Microsoft has elected to include extensions for asm.js in its Chakra JavaScript engine. (Chrome may be following suit as well.)

Mozilla provided a big example for 64-bit asm.js: "browser-based games that deliver performant, native-like gameplay, such as those built with Epic Games' Unreal Engine," featuring assets that are "often much larger than we expect from traditional Web applications." With 64-bit address space at one's disposal, it's easier to load and process those assets, but there are ostensibly other applications for a larger address space beyond gaming.

Firefox was previously available in 64-bit editions for Mac OS X and Linux, but Windows still accounts for the majority of Firefox's market share. An earlier effort to put a 64-bit edition of Firefox into the hands of Windows users stalled in 2012, with the lack of 64-bit plug-ins for Firefox cited as a big reason.

But strong backlash from users prompted Mozilla to reconsider, although it has made no promises as to when a 64-bit version will be released to the general public. Native HTML5 functionality has eclipsed traditional plug-ins -- from replacing Flash to playing back encrypted video content -- so it's easier to deliver a native 64-bit browser.

Mozilla is holding off on delivering a 64-bit browser for users to focus on higher-priority projects -- for example, Firefox OS, set to debut next year on phones in major markets.

Copyright © 2015 IDG Communications, Inc.

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