We’ve all been there. You turn on your PC, and instead of getting straight to work, you’re faced with horrific slowdown and loud-running fans. Hit Ctrl + Shift + Escape, and you see that your CPU usage is inexplicably at 100%.
It’s a common problem that’s, luckily, not usually too hard to solve. Here are several fixes for the 100% CPU usage problem.
Check Your Power Supply
This one’s an issue that can affect both desktop and laptop Windows 10 users. If you have a faulty power supply (the mains cable on a laptop, the PSU in a desktop), then it can automatically start undervolting your CPU to preserve power. When undervolted, your CPU can function at only a fraction of its full power, hence the possibility of this manifesting as 100% CPU usage on Windows 10.
To solve this on a laptop is quite simple: unplug your laptop from the power cable, then click the battery icon at the bottom right corner of your Windows 10 desktop -> Battery Settings -> Power & Sleep Settings -> Additional power settings, and select High Performance. If the issue was with your power supply, the CPU usage should return to normal in the task manager (Ctrl + Shift + Esc).
On a desktop things can be a little more complicated, as you’ll need to physically remove the PSU from your PC and test a different one. We recommend going through our other tips listed below before trying this.
Disable Superfetch (or Windows Search)
Superfetch is a process by which Windows 10 learns which apps you use most often, then pre-fetches them for you so they load quicker each time you use them. It’s a constant background process that doesn’t usually cause problems, but it doesn’t always play nice with older devices.
To find out whether Superfetch (or another service) is hogging your CPU, open Task Manager (Ctrl + Shift + Escape), click “More details,” then click “CPU” to order processes by how much CPU they’re using.
If you see that a “Service Host” like Superfetch or something else is using a lot of CPU, you can try right-clicking it and clicking “End process.”
Alternatively, to disable it permanently (or until Windows switches it on again, which can happen after you update the OS), press Win + R, type
services, then in the Services window scroll down to Superfetch.
Right-click Superfetch, click Properties, then in its Properties window click the drop-down next to “Startup type,” click “Disabled,, and OK.
You can technically do this to any service that’s hogging CPU, but some services are system-critical so you need to be careful. Another culprit of high CPU usage is ‘Windows Search,’ which you can safely disable, too.
Reset Your Power Plan
Twiddling around in Windows’ power options can have a substantial effect on your PC performance. If you’re set to “High performance” – particularly if you made tweaks to the “plan settings” – then it’s possible that you’re overloading your CPU (again, older devices are susceptible to this).
power plan into the Start search bar then click “Choose a power plan.” If you’re on “High performance” or “Power Saver,” then switch to “Balanced.”
For extra certainty, click “Change plan settings,” then on the new screen click “Restore default settings for this plan.”
Disable Third-Party Antivirus Software
This one may be a bit contentious, but our view here is that if you’re using antivirus software on Windows 10, then you’re probably putting unnecessary strain on your CPU (particularly if its older). It doesn’t usually hurt to have the extra security, but you probably don’t need it.
Every year, we write an in-depth feature about Windows 10’s onboard security software, Windows Defender, and every year it gets better and better. At this point, it’s more or less on par with the best antivirus software out there.
So don’t be afraid to disable your third-party antivirus software to see if it helps your CPU usage. If it does, then uninstall it, because Windows Defender should really have you covered.
Identify Errors in Specific Processes
This one’s a little more intricate than the other fixes but also has the potential to offer more long-term solutions to your CPU woes.
If you’ve found that your high CPU usage is being caused by a Windows “Service Host” process in Task Manager, then one option is to take the Superfetch route as per the first fix and disable it.
But to go deeper into the problem, press Win + R, then open “eventvwr.” Here in the pane one the left, go to “Applications and Service Logs -> Microsoft -> Windows -> WMI-Activity -> Operational..
Check the middle column, called “Operational,” for errors, then under the “General” tab below that check the “ClientProcessId” number.
Go back to Task Manager, click the “Details” tab, then sort the processes by “PID.” Find the process with the error, right-click it and click “Open file location.” This will give you an idea of what software the process is attached to and whether you can reinstall it, uninstall it, update its drivers and so on.
100% CPU usage on Windows 10 is a multi-faceted and complex issue with many solutions. These are some of the most likely fixes, but if you’ve found that something else worked better, then let us know in the comments!
This article is updated in November 2019.