How to Fix 100% CPU Usage in Windows 11 and 10

When the processor stays at or near 100%, everything slows down: apps take longer to open, the mouse can lag and the fans may run loudly, even when you aren't doing much. The steps below help you find the cause and fix it in Windows 11 and Windows 10, starting with the quickest checks.

1. Find What's Using Your CPU in Task Manager

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Start by finding out which app or process is responsible. Task Manager groups everything that's running into apps, background processes and Windows processes.

1. Press Ctrl + Shift + Esc to open Task Manager. On Windows 10, select More details if you only see a short list of apps.
2. Select Processes, then select the CPU column heading so the busiest items are at the top.
3. Open the Performance tab to watch the CPU graph over a minute or two.
4. If the top item is an app you opened yourself, save your work and close it, or select it and choose End task.

Don't end Windows processes you don't recognize, and never stop your antivirus. Search for the process name first. Note the name of anything that keeps returning to the top: you'll need it in the steps below.

Expected result: CPU use drops once the busy app is closed, or you know which program to deal with.

2. Restart Your PC

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A restart closes apps and background tasks that have piled up and finishes any update that is waiting. Select Start > Power > Restart.

Expected result: after you sign in and wait a few minutes, CPU use settles at a lower level.

3. Install Windows Updates

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Updates often include fixes and performance improvements, including newer drivers in the optional updates.

1. Windows 11: select Start > Settings > Windows Update > Check for updates. Windows 10: select Start > Settings > Update & Security > Windows Update > Check for updates.
2. Select Download & install for anything that's available, including drivers under Advanced options > Optional updates (Windows 10: View optional updates).
3. Restart if Windows asks you to.

Expected result: Windows Update says you're up to date.

4. Scan for Malware With Windows Security

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Malware can run in the background and keep your processor busy.

1. Windows 11: select Start > Settings > Privacy & security > Windows Security > Virus & threat protection > Quick scan.
2. Windows 10: select Start > Settings > Update & Security > Windows Security > Virus & threat protection, then Quick scan.

Expected result: the scan reports no current threats, or removes what it found.

5. Use Only One Antivirus App

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Running two antivirus apps that both scan in real time doesn't double your protection. Microsoft warns that when Microsoft Defender Antivirus and another antivirus both try to provide active protection, it affects performance and isn't supported. Normally, Windows 11 and 10 turn Microsoft Defender Antivirus off automatically when you install another antivirus.

1. Open Windows Security and select Virus & threat protection.
2. Under Who's protecting me?, select Manage providers to see which antivirus is turned on.
3. If you have more than one antivirus app installed, keep the one you want and uninstall the others in Settings > Apps > Installed apps (Windows 10: Apps & features).

Expected result: one antivirus app is listed as turned on.

6. Turn Off Startup and Background Apps You Don't Need

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1. Press Ctrl + Shift + Esc, select Startup apps (Windows 10: the Startup tab), right-click an app you don't need straight away and choose Disable.
2. Windows 11: in Settings > Apps > Installed apps, select More options (…) > Advanced options next to an app and set Let this app run in the background to Never. Windows 10: Settings > Privacy > Background apps.

Startup apps are covered step by step in How to Fix Slow Startup in Windows 11.

Expected result: fewer apps are running after you restart and sign in.

7. Check Your Power Mode and Visual Effects

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Power mode changes how Windows balances speed against power use, and visual effects add work every time a window opens or moves. Both are on Microsoft's list of performance fixes.

1. Windows 11: select Start > Settings > System > Power & battery, and under Power mode choose Balanced or, when plugged in, Best performance. Windows 10: select Settings > System > Power & sleep > Additional power settings, then choose Balanced or, when plugged in, High performance (select Show additional plans if you don't see it).
2. To reduce the work Windows does drawing the screen, select Start, type Adjust the appearance and performance of Windows, and on the Visual Effects tab select Adjust for best performance > Apply.

Best performance uses more power and drains a laptop battery faster. If you can't change the power mode, open Control Panel > System and Security > Power Options and select Balanced first.

8. Find a Conflicting Program With a Clean Boot

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If you can't tell which program is to blame, a clean boot starts Windows with only essential drivers and startup programs. If the CPU is calm in a clean boot, something you turned off is the cause.

1. Sign in with an administrator account, search for msconfig and open System Configuration.
2. On the Services tab, select Hide all Microsoft services, then Disable all and Apply.
3. On the Startup tab, select Open Task Manager, disable each enabled startup item and write down which ones you disabled.
4. Close Task Manager, select OK in System Configuration and restart.
5. If the CPU is calm, turn half of the services and startup items back on and restart. Keep halving the list until the high CPU returns, and you have found the cause.

To go back to normal: in System Configuration select General > Normal startup, clear Hide all Microsoft services on the Services tab and select Enable all, turn your startup apps back on in Task Manager, then restart.

Expected result: you find the program or service that drives the CPU to 100%. Microsoft suggests contacting its maker to see whether the problem can be fixed, or leaving it turned off.

Still at 100%? What to Try Next

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• Update the driver for the device involved: right-click Start, select Device Manager, right-click the device and choose Update driver. See How to Update Drivers.
• Repair Windows system files: see How to Repair System Files Using System File Checker.
• Older hardware: Microsoft notes that older PCs may see little improvement from these steps, and upgrading may be the best long-term option.