Fast User Switching can be handy, but also comes with downsides. Here’s how to disable it on all versions of Windows, if you want to.
Fast User Switching allows users to sign into a computer while other users are still signed in. While it offers the obvious advantage of not forcing other users to sign out before you can sign in with your own account, it does have some disadvantages. As long as other users are signed in, Windows is using extra resources on them—especially if they have left resource-intensive apps or background services active. If other users are signed in, you also cannot restart or shut down the PC without having them sign out or risk losing any open files they haven’t saved. If you do have multiple users on your PC and you’d rather not have Fast User Switching available, you just have to make a quick edit to the Windows Registry or Local Group Policy Editor.