Disk Cleanup is an essential Windows system tool which allows you to delete various unnecessary files created by the OS to save your hard disk space. By default it works in a simpler mode which allows you to delete only files related to your current user account. You can switch it to the extended mode, which allows you delete more unused files used by Windows Updates, or service packs and so on. When you start the Disk Cleanup app, you have to switch every time to the extended mode by clicking the Clean up system files button. Thus it has to calculate how much disk space you will free up twice which may take a lot of time. It is possible to speed this up and open the extended mode directly. Let's see how.