Version 55.0, first offered to Release channel users on August 8, 2017
Today's release brings innovative functionality, improvements to core browser performance, and more proof that we’re committed to making Firefox better than ever. New features include support for WebVR, making Firefox the first Windows desktop browser to support VR experiences. Performance changes include significantly faster startup times when restoring lots of tabs and settings that let users take greater control of our new multi-process architecture. We’ve also upgraded the address bar to make finding what you want easier, with search suggestions and the integration of our one-click search feature, and safer, by prioritizing the secure - https - version of sites when possible. Read what Nick Nguyen (VP, Firefox Product) has to say about Firefox 55, get historical perspective on the development of WebVR from Sean White (SVP, Emerging Technologies) in this Medium post, and read about all the new features for developers in Firefox 55 on Mozilla Hacks.
We'd also like to extend a special thank you to all of the new Mozillians who contributed to this release of Firefox!
Launched Windows support for WebVR, bringing immersive experiences to the web. See examples and try working demos at Mozilla VR.
Added options that let users optimize recent performance improvements
Setting to enable Hardware VP9 acceleration on Windows 10 Anniversary Edition for better battery life and lower CPU usage while watching videos
Modernized application update UI to be less intrusive and more aligned with the rest of the browser. Only users who have not restarted their browser 8 days after downloading an update or users who opted out of automatic updates will see this change.
Firefox does not support downgrades, even though this may have worked in past versions. Users who install Firefox 55+ and later downgrade to an earlier version may experience issues with Firefox.
Made the Adobe Flash plugin click-to-activate by default and allowed only on http:// and https:// URL schemes. (This change will not be visible to all users immediately. For more information see the Firefox plugin roadmap)