Windows showing 100% disk usage? Here’s how to fix it and get your PC responsive again.
What’s Using My Disk?
Press Ctrl + Shift + Esc → Performance tab → Open Resource Monitor.
Click Disk → sort by Activity to see which process is hammering your disk.
Common culprits: Windows Update, Superfetch, antivirus real-time scanning.
Fix 1: End High-Disk Processes
In Task Manager → Processes tab → sort by Disk.
End any process with very high disk usage that you don’t need right now.
Don’t end system processes (anything by Microsoft Corporation or Windows).
Fix 2: Disable Superfetch (SysMain)
Press Win + R, type services.msc, press Enter.
Find SysMain → right-click → Properties → Stop.
Startup type: Disabled.
Reboot. On SSDs this is less of an issue — consider re-enabling if you have an SSD.
Fix 3: Change Virtual Memory
Press Win + R, type sysdm.cpl, press Enter → Advanced tab → Settings → Advanced tab → Change.
Uncheck Automatically manage paging file size for all drives.
Select your drive → Custom size: Initial: 4096, Maximum: 8192 → Set → OK → restart.
Fix 4: Run Disk Cleanup
Press Win + R, type cleanmgr, press Enter.
Select drive → Clean up system files.
Check everything, especially:
- Windows Update Cleanup
- Previous Windows installations
- Recycle Bin
- Temporary files
Fix 5: Disable Windows Search Indexing
Press Win + R, type services.msc, press Enter.
Find Windows Search → right-click → Properties → Stop → Startup type: Disabled.
Fix 6: Check for Windows Update Issues
Settings → Windows Update → View update history.
If a recent update is the problem, uninstall it: Settings → Windows Update → Recovery → Go back to previous version of Windows.
Fix 7: Consider an SSD
If your PC is still on a mechanical HDD, upgrading to an SSD is the single biggest performance improvement.
A 500GB SATA SSD costs around $40. Clone your drive with free software like Macrium Reflect.
Still 100% disk? Your hard drive is likely failing. Back up your data immediately and run CrystalDiskInfo to check drive health.