Windows 11 High CPU Usage: Find the Cause and Fix It

Windows 11 high CPU usage shows up as a fan that never stops, a laptop that runs hot and a PC that stutters when you type or switch windows. Short spikes are normal: Windows does a lot of work for a few minutes after sign-in, during updates and while Microsoft Defender scans files. The problem is CPU usage that stays at 80 percent or more for long stretches, especially when you are not doing anything demanding.

The key is to identify the process responsible before you change anything. This guide works on Windows 11 version 24H2 and 25H2, Home and Pro.

Step 1: Find the process in Task Manager

1. Press Ctrl + Shift + Esc to open Task Manager.
2. On the Processes page, select the CPU column header so the busiest processes are at the top.
3. Watch for a minute. Note any process that stays near the top, and expand grouped entries (such as Service Host) to see which service is inside.
4. For more detail, open the Performance page to see overall CPU usage and clock speed, or type resmon in Start to open Resource Monitor, whose CPU tab has an Average CPU column that smooths out brief spikes.

If the process is an app you recognise, right-click it and select End task (save your work first). Task Manager in Windows 11 also offers Efficiency mode, which lowers the priority of a selected app’s process so it competes less with what you are doing.

Step 2: Match the culprit to a fix

Process in Task Manager	What it is	What to do
Your browser	Busy tabs and extensions	Close heavy tabs, disable extensions you do not need, update the browser.
Antimalware Service Executable	Microsoft Defender scanning	Let the scan finish. If it is constant, run a full scan and check for another antivirus also running.
Service Host: Windows Update, Windows Modules Installer Worker	Updates being downloaded and installed	Let it finish, then restart.
Microsoft Windows Search Indexer	Building the search index	Normal after big file changes; it should settle.
System interrupts	Hardware and drivers	Update drivers, unplug USB devices one at a time.
An unknown or oddly named process	Possibly unwanted software	Right-click > Open file location, then scan it with Windows Security.

Do not end Windows processes you do not recognise just to lower the number; some of them are needed to keep Windows running. If update activity never ends, restart once, then check Settings > Windows Update for an error message to look up.

Step 3: Cut down background and startup apps

Many PCs are slowed by apps that start with Windows and run all day: chat apps, launchers, updaters and cloud sync tools.

1. Open Settings > Apps > Startup.
2. Turn off anything you do not need the moment you sign in. You can still open these apps normally later.
3. Uninstall apps you no longer use from Settings > Apps > Installed apps, especially preinstalled trial software.

Our Windows 11 startup apps guide explains which items are safe to switch off.

Step 4: Check power mode, drivers and heat

Power mode. Go to Settings > System > Power & battery and look at Power mode (Best power efficiency, Balanced or Best performance). On a power-saving setting the processor runs slower, so the same work shows a higher CPU percentage. On a laptop, plug in the charger and try Balanced.

Drivers. High CPU from System interrupts, or spikes that began after new hardware, usually come from drivers. Install everything in Settings > Windows Update, including Advanced options > Optional updates, and download chipset, graphics and network drivers for your model from the PC or component maker.

Heat. When a processor gets too hot it slows itself down, so everything takes longer and usage looks higher. Make sure vents are not blocked, use a laptop on a hard surface, and have dust cleaned out of an older desktop or laptop.

Step 5: Scan for malware

Unwanted software, including hidden cryptocurrency miners, can keep the CPU busy around the clock.

1. Open Windows Security > Virus & threat protection.
2. Select Scan options, choose Full scan and select Scan now.
3. If you suspect something is hiding, run the Microsoft Defender Antivirus (offline scan) option from the same page. The PC restarts to perform it.

More on Microsoft’s built-in protection is in our Windows 11 Defender guide.

Step 6: Isolate the cause with safe mode or a clean boot

If you cannot see a clear culprit, or the busy process is a generic one such as Service Host, check whether the problem survives with third-party software out of the way.

• Start in safe mode. If CPU usage is normal there, a driver or startup app is responsible.
• For a clean boot, press Windows key + R, type msconfig, go to the Services tab, tick Hide all Microsoft services and select Disable all. Disable startup items in Task Manager, then restart. Re-enable items in small groups until the problem returns. Undo the changes afterwards by choosing Normal startup on the General tab.

Step 7: Repair Windows files

If Windows components themselves misbehave, repair the system files. Right-click Start, select Terminal (Admin) and run:

sfc /scannow

If SFC reports files it could not fix, run DISM /Online /Cleanup-Image /RestoreHealth, restart and run sfc /scannow again. Our guides to SFC and DISM explain the results.

Last resorts

If the problem started after a specific update, uninstall it from Settings > Windows Update > Update history > Uninstall updates. Settings > System > Recovery offers Fix problems using Windows Update, which reinstalls the current version of Windows while keeping your apps and files, and Reset this PC, which reinstalls Windows and can keep your files. Back up first.

If CPU usage is still abnormal on a freshly reset system, suspect hardware or cooling. For general sluggishness that is not tied to the CPU, see our Windows 11 slow performance guide.

New to Task Manager? Our guide to Task Manager in Windows 11 explains each page and how to end a frozen app safely.