Mozilla has finally, finally introduced a 64-bit version of Firefox for Windows with the recent release of Firefox 43. There were already 64-bit versions for Mac and Linux. Windows users, however, were left with 32-bit Firefox like a bunch of suckers.
No more! Users running Windows 7 and up can download and install Firefox 64-bit. It’s not clear if Mozilla’s Firefox site is set-up to auto-detect a 64-bit Windows system. For now, it’s easier to grab the new version from the all downloads page. Just scroll towards the bottom until you find “English (US)” and click the Windows 64 icon.
If you're running Firefox 42 and do an in-place upgrade to version 43 you’ll remain on the 32-bit version.
The impact on you at home: Once you install 64-bit Firefox—assuming you are also running a 64-bit version of Windows—it will be hard to tell the difference between it and the 32-bit version. Most of the big improvements happen behind the scenes, although the 64-bit version should be able to keep more tabs open without slowing as well as run web apps that require 64-bit support. 64-bit programs are able to address more than 4GB of memory, allowing for better performance.
The one thing you will notice is that some plugins simply won’t work with Firefox's 64-bit version. This is part of Mozilla’s plan to cease support for NPAPI plugins such as Java and Silverlight. (Other browser makers are taking similar actions.) That said, Flash will continue to be available owing to its popularity for web video.
Beyond the 64-bit switch, Firefox 43 also brings search suggestions to the Awesome Bar, and better on-screen keyboard compatibility for touch devices running Windows 8 and up.