Microsoft’s October 16, 2026, Windows 11 Release Preview notes describe a change that lets Windows send qualifying Microsoft Edge launches straight to an instance already running in the background, bypassing a temporary intermediary process. The feature is rolling out gradually, so installing update KB5127936 does not mean it is active on every device. Microsoft’s Release Preview notes cover Windows 11 25H2, build 26200.9807, and 26H2, build 26300.9807.
How Edge’s warm launch works
A warm launch is a request to open an app that is already running in the background. When someone launches Edge from a link, the taskbar, or the Start menu, Windows can route that request to the existing Edge instance instead of first starting a temporary process to pass it along. Microsoft says the shorter route helps Edge respond faster, particularly when other apps are open.
That condition matters: the feature concerns Edge already running in the background. In a qualitative test reported by Windows Latest, its reporter saw quicker Edge launches with Microsoft Store and Paint open on a virtual machine with 4 GB of RAM after installing the update. The reporter described the launch immediately after a restart as unchanged.
Startup boost is a separate Edge setting
Edge’s Startup boost prepares core browser processes in the background while the browser is closed. Accelerated warm launch changes how Windows routes a request to an Edge instance already running in the background; Startup boost is a separate feature. Microsoft says you can check or toggle Startup boost in Edge at edge://settings/system/manageSystem. Microsoft Support explains the setting.
What app developers can use
Microsoft also describes accelerated warm launches as a capability other Windows apps can adopt. Its developer documentation treats the APIs as a Limited Access Feature, with an unlock-token request. The examples cover Start-menu tile and protocol launches, and apps must retain their own single-instance handling. Microsoft notes that the capability does not cover every launch source, application, or Windows version. Microsoft’s developer documentation
