Certain apps or viruses can also lead to full disk usage. There might be many reasons which are forcing your Hard Drive to perform at max rate. Under the process tab, you can track your Disk Usage here.
Right-click on your taskbar and select task manager or you can use the keyboard shortcut key Ctrl + Shift + ESC. To check that your disk usage has reached 100% you have to navigate through Task Manager. Here are some of the best ways to reduce Disk Usage in Windows 10. Applications will lag and will not work smoothly at all. Full Disk Usage can freeze your system completely. This problem can result in the overall slow performance of your system. 100% Disk usage problem has become common for Windows 10 users.