If you’ve observed an unusual spike in CPU usage (sometimes at 100%) following the installation of a Windows update in either Windows 11 or Windows 10, this guide will help you identify the potential cause and offer solutions to resolve the issue.
Also see: How to Limit CPU Usage of a Process in Windows 11
Slow hard drive leads to high CPU usage after Windows Update
Let’s start with the solution that I’ve used to fix similar problems on one of our office laptops that runs on Windows 11. The laptop had been left turned off for a few months, and when we turned it on, Windows Update obviously ran to apply any patches that the laptop had missed out.
What’s strange is that after applying the update (and during the update as well), the CPU usage spiked to 100% and seemed to not go down even when the computer was idle. Later, we found out that it was the hard drive that was causing the issue. We ran a defragmentation for the laptop, and the issue was resolved.
So what we learn here is that if you have a laptop or desktop computer that has been left off for a long time, or if you are still using an old hard drive rather than an SSD, as you turn it on and Windows Update starts running and installing necessary updates and patches, you will likely see high CPU usage after that if the hard drive cannot keep up with the heavy read and write requests.
Suggested read: Why is My Memory Usage So High When Nothing is Running?
To address the problem of high CPU usage caused by a slow and fragmented hard drive, you can defragment the disk to improve its performance. Follow these steps to defragment your hard disk drive in Windows 11 or Windows 10:
- Press the Win + E to open File Explorer and navigate to “This PC“.
- Right-click on the system drive (usually the C: drive) and select “Properties“.
- Go to the “Tools” tab and click on “Optimize“.
- Select the system drive and click “Optimize” to defragment it.
While Windows’ default defragmentation tool is usually sufficient to defragment most of your hard drives, you may choose to use a third-party defragmentation tool for slightly better optimization.
Run CHKDSK to check your system drive for errors
Sometimes, a high CPU usage issue can occur due to errors on your system drive or any drive that your system uses. Running CHKDSK (Check Disk) can help identify and fix any errors. Here’s how to do it in Windows 11 or Windows 10:
- Go to the Start menu and search for “Command Prompt“.
- Right-click it and select “Run as administrator“.
- Type “
chkdsk c: /f /r” (replace C: with the actual drive letter you want to run chkdsk on) and press Enter.
- Type “Y” and press Enter to schedule the disk check for the next restart (if the disk is currently in use).
- Restart your computer, and the disk check will run.
It may take up to several hours for the chkdsk process to complete. If you have a huge drive that chkdsk needs to run on, you may want to leave it running overnight. After checking and repairing the disk, see if the Windows 11/10 high CPU usage after update is resolved.
Check if Windows Update is still running
If CPU usage spikes up only after installing a recent Windows Update, check if the Windows Update has completed its installation. There are updates that may require several restarts before they can be installed successfully.
There are also times when these updates may fail to install. When that happens, you need to check the Windows Update and make sure all updates have been installed. When in doubt, click “Check for updates” again to make sure everything is up to date.
To check if a Windows Update is still running, follow these steps:
- Press the Win + i to open Settings.
- Click on “Windows Update” from the left pane.
- Check if there is any update in progress. If there is, click “Install updates” or “Restart now” to continue the installation.
Restart your computer
Another solution would be to do a quick reboot and see if the problem resolves itself. There are times when things such as programs and services may be stuck running even though they should have been finished, causing endless requests from CPU resources and resulting in high CPU usage. Try to restart your computer.
Related tip: How to Delete Windows Update Files in Windows 11
Revert the update
If you’re sure that a Windows update has caused high CPU usage on your computer and slowed down your PC, you can try reverting the update. Here’s how to do it:
- Press the Win + i on your keyboard to open the Settings app.
- Click on “Windows Update” on the left-hand side, then click on “Update history“.
- Click on “Uninstall updates“.
- A new window will open with a list of all the updates installed on your computer. Find the update that you suspect is causing the high CPU usage and click on it.
- Click on “Uninstall” and follow the instructions to complete the process.
- Once the update is uninstalled, restart your computer and check if the high CPU usage issue has been resolved.
Alternatively, you can also try to rollback your Windows 11/10 to an earlier build if it was a major update.
Temporarily disconnect other external devices
Try temporarily disconnecting external devices such as external hard disk drives, printers, or other USB devices that are connected to your computer. Some devices may interfere with Windows updates or cause conflicts that result in high CPU usage.
Identify the process that is using up the CPU resources
You can use the Task Manager to identify the process that is using up the CPU resources. Here’s how to do it:
- Press the Ctrl + Shift + Esc keys on your keyboard to open the Task Manager.
- Click on the “Processes” tab.
- Click on the “CPU” column header to sort the processes by CPU usage.
- Identify the process that is using up the most CPU resources.
- Right-click on the process and select “End task” to stop the process.
Note that ending a process may cause the program associated with it to stop working or crash. If you’re unsure which process to end, you can do a quick online search for more information about the process.
Windows Update conflicts with other software
Sometimes, third-party software installed on your computer may conflict with Windows Update and cause high CPU usage. To resolve this, try disabling or uninstalling any software that you suspect may be causing the issue. You can also try updating the software to its latest version.
Other things you can try to fix 100% CPU usage
Here are some other things you can try to resolve high CPU usage issues after a Windows Update:
- Disable startup programs: Some programs may be set to run automatically when you start your computer, causing high CPU usage. You can disable these programs from the Task Manager’s “Startup” tab.
- Disable unnecessary services: Some Windows services may not be necessary for your computer and may cause high CPU usage. You can disable these services from the “Services” app.
- Run System File Check and DISM: These built-in Windows utilities can help you fix any corrupted system files that may be causing high CPU usage. To run them, open the Command Prompt as an administrator and type “sfc /scannow” followed by “DISM /Online /Cleanup-Image /RestoreHealth”.
- Check your power plan in Windows 11 or 10: Your computer’s power plan may affect how much CPU resources are used. Try setting it to “High performance” and see if the issue is resolved.
In conclusion, a high CPU usage after a Windows update in Windows 11 or Windows 10 can be frustrating and disruptive, but it can often be resolved with the right troubleshooting steps. We have discussed several potential causes of this issue, including disk drive problems, system errors, and background processes. If you’ve tried all the solutions listed here and the problem still persists, you may need to seek help from a professional technician.