UPDATE 2017-08-14: 64-bit Firefox is now the default on 64-bit Windows.
On December 15, 2015 we released the 64-bit Firefox web browser for Windows 7 64-bit systems. This browser version offers gains in performance for Firefox users with 64-bit PCs. We’re pleased to offer it to users of Windows 7 and above who are looking for added performance for applications and games while running the Firefox web browser. This version offers improvements over the 32-bit version of Firefox.
Firefox 64-bit for Windows, by design, has limited support for plugins. Users will notice that certain sites requiring plugins that worked in previous 32-bit versions of Firefox might not work in this 64-bit version. As we’ve shared previously, Mozilla intends to remove support for most NPAPI plugins in Firefox by the end of 2016. (Update – Mozilla removed support for NPAPI plugins when it shipped Firefox 52 on March 7, 2017)
Download. Try It. Give Us Feedback.
We’re counting on your feedback to continue improving Firefox with 64-bit support. You can also read up on Firefox 64-bit in our Support community.