macOS方面的改进就更大一些，WebGL电源首选项允许非性能关键应用程序和applet在多GPU系统中请求低功耗GPU而不是高功率GPU，这有助于省电，并且macOS上的运行效率，尤其是一直被诟病的标签页切换速度也得到了提升。

下载地址:

http://ftp.mozilla.org/pub/firefox/releases/63.0b12/

更新列表:

New

• 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
• Improved Windows 10 integration: your Firefox theme now matches your OS Dark / Light mode
• WebExtensions now run in their own process on Linux
• Faster tab switching in the majority of cases for our macOS users
• Improved the reactivity of Firefox on macOS

Changed

• In the Library, the Open in Sidebar feature for individual bookmarks was removed
• Never check for updates option removed from about:preferences. If a substitute is needed, we recommend using the DisableAppUpdate enterprise policy
• Firefox now warns about having multiple windows/tabs open when quitting from the main menu.
• 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 your preferences
• The build infrastructure of Firefox on Windows moved to the Clang tool chain, bringing important performance gains

Developer

• Changes affecting developers