Microsoft Edge is rolling out two new features – vertical tabs and startup boost. Vertical tabs feature is designed to move the tabs bar from the top to the left side in a vertical layout. Startup boost will automatically maximize your device performance by reducing the time it takes to open the browser after a device reboot or reopening the browser. Later this month, vertical tabs is also getting support for drag and drop, which will allow you to drag links from the open tab and drop it in the vertical tab sidebar.
Source: https://www.bleepingcomputer.com/news/microsoft/microsoft-edge-is-now-41-percent-faster-with-new-startup-boost-feature/