The Firefox 63 web browser promises to allow WebExtensions, the cross-browser system for developing extensions, to run in their own process on Linux-based platforms, as well as to improve the Windows 10 integration by making the Firefox theme match host’s Dark or Light mode. On Apple’s macOS platform, Firefox 63 will bring faster tab switching, improve Firefox’s reactivity, and allow non-performance-critical apps to request the low-power GPU instead of the high-power GPU in Macs with multiple graphics cards via the WebGL power preferences.