Firefox Release Notes

Performance and visual improvements for Windows users

• Moved the build infrastructure of Firefox on Windows to the Clang toolchain, bringing important performance gains
• Firefox theme now matches the Windows 10 OS Dark and Light modes

Performance improvements for macOS users

• Improved reactivity
• Faster tab switching
• 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

Added content blocking, a collection of Firefox settings that offer users greater control over technology that can track them around the web. In 63, users can opt to block third-party tracking cookies or block all trackers and create exceptions for trusted sites that don’t work correctly with content blocking enabled.

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.

Firefox now recognizes the operating system accessibility setting for reducing animation

Added search shortcuts for Top Sites: Amazon and Google appear as Top Sites tiles on the Firefox Home (New Tab) page. When selected these tiles will change focus to the address bar to initiate a search. Currently in US only.

Resolved an issue that prevented the address bar from autofilling bookmarked URLs in certain cases

Various security fixes

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.

Refreshed visual style of Developer Tools menus to improve navigation and consistency

The Dev Tools accessibility inspector is now enabled by default. This tool surfaces information exposed to assistive technologies on the current page, allowing you to check what’s missing or otherwise needs attention.

Added support for Web Components custom elements and shadow DOM

The inspector now ships with a Font Editor that allows you to control non-variable as well as variable fonts

Quick Heal internet security software might crash 32-bit Firefox on Windows. A workaround is documented from this support article until a fixed version of Quick Heal is available.