Firefox Nightly
Release Notes

WebExtensions now run in their own process on Linux

Firefox now warns about having multiple windows and tabs open when quitting from the main menu. The Save and Quit feature has been removed. You can restore your session by ticking the box for Restore previous session in the General → Startup options or by using Restore Previous Session in the main menu.

Improved page load performance by blocking cross-site tracking

On macOS, WebGL power preferences allow non-performance-critical applications and applets to request the low-power GPU instead of the high-power GPU in multi-GPU systems

Multiple tabs can now be selected using Ctrl/Cmd and Shift. These selected tabs can be muted, moved, bookmarked, pinned, and more simply and quickly.

Improved Windows 10 integration: your Firefox theme now matches your OS Dark / Light mode

Firefox by default now prompts for permission before allowing pages to automatically play media with sound

Faster tab switching in the majority of cases for our macOS users

Improved the reactivity of Firefox on macOS

TLS certificates issued by Symantec are no longer trusted by Firefox Nightly. Website operators are strongly encouraged to replace any remaining Symantec TLS certificates before Firefox 63 final release on October 23.

In the Library, the Open in Sidebar feature for individual bookmarks was removed

The option to Never check for updates was removed from about:preferences. You can use the DisableAppUpdate enterprise policy as a substitute.

The Ctrl+Tab shortcut now displays thumbnail previews of your tabs and cycles through tabs in recently used order. This new default behavior is activated only in new profiles and can be changed in preferences.

The build infrastructure of Firefox on Windows moved to the Clang tool chain, bringing important performance gains