100% CPU Usage in Windows? Here’s How to Fix it

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 will 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 in Windows.

Also read:Hidden Windows 11 Features for Power Users

Disable SysMain (formerly known as Superfetch)

SysMain 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. This used to be known as Superfetch in older versions of Windows 10.

To find out whether SysMain (or Superfetch) 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 SysMain 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 SysMain, 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.

Also read:5 Ways to Stop ‘100% Disk Usage’ Problems on Windows

WMI Provider Host Using 100% CPU

The WMI (Windows Management Instrumentation) Provider Host is a core service on Windows that links up with various software on your PC to send it information about your operating system. In other words, it’s a very important process, and you shouldn’t disable it lightly. If, however, you see in the Task Manager Processes tab that it’s using a lot of CPU, then of course you should do something about it.

The first thing you can try is restarting the WMI service. Go to the Services app. (You can get there quickly by typing services in a Start menu search). Scroll down to Windows Management Instrumentation, right-click it, then click Restart.

If that doesn’t work, then the next solution is a little more intricate but also has the potential to offer more long-term solutions for your CPU woes.

If your 100% CPU usage is being caused by the WMI Provider Host process in Task Manager, then you can delve deeper into the problem. Press Win + R ,then open “eventvwr.” Here in the pane on the left, go to “Applications and Service Logs -> Microsoft -> Windows -> WMI-Activity -> Operational.” This will show you all the processes that the WMI Provider Host is dealing with.

Check the middle column, “Operational,” look for errors in the service, then under the “General” tab below that, check the “ClientProcessId” number. This should help you zoom in on the app or process clogging up your WMI Provider Host service.

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.

There may be multiple errors like this in the WMI Provider Host, in which case you should repeat the above process to address the different errors. It’s also possible that just one app/process has been hogging your CPU all this time, in which case you should be good to go after you’ve dealt with the culprit.

Also read:How to Fix TiWorker.exe High CPU or Disk Usage Issues

Reset Your Power Plan

Twiddling around in Windows’s 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.)

Windows 10

In Windows 10, type power plan in 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.”

Windows 11

In Windows 11, type power plan , then in the “Power & battery” window click “Power mode” and “Best performance.”

Also read:How to Choose the Right CPU Cooler

Check Your Power Supply

This one’s an issue that can affect both desktop and laptop Windows 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.

To solve this on a laptop is quite simple: unplug your laptop from the power cable, then follow our instructions in the previous section to set its power plan to ‘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.

100% CPU Usage in Games

Most games tend to be GPU-intensive rather than CPU-intensive, so shouldn’t really be hammering your CPU too hard. So if you run a game and shoot up to 100% CPU usage, there might be a problem you have to intervene in as it can cause performance bottlenecks and an ugly “dragging” effect.

Before the game-specific tips below, you should try temporarily turning off real-time protection in Windows Defender when you play, as some people have reported this to cause high CPU usage while gaming.

To do this, in Windows go to “Settings -> Privacy & security (Update & security in Windows 10) -> Windows Security -> Virus & threat protection -> Manage settings”.

Here, switch the ‘Real-time protection’ slider to “Off”. We recommend you switch this back on after gaming.

Fix 100% CPU Usage in Warzone

Activision Blizzard’s free-to-play battle royale game – a kind of standalone expansion to Call of Duty: Modern Warfare – isn’t terrible well optimized, and to fix its high CPU usage problem you need to play around in Task Manager.

Go to Task Manager by pressing Ctrl + Shift + Esc, click the Details tab, then right-click “ModernWarfare”.

In the context menu, go to “Set priority” then change the game’s priority to “High”.

Note: If you’re experiencing high CPU usage in other games, this tip may also solve that problem.

Fix 100% CPU Usage in Apex Legends

High-flying battle royale game Apex Legends should not be rinsing your CPU, but if it is, then the good people of the gaming community have a good workaround for you.

The most popular fix for high CPU usage while playing Apex Legends involves going to the game’s graphics settings and take a look at your v-sync settings. If your v-sync is disabled, switch it to “Dynamic”, apply, then switch back to Disabled.

Conversely, if your v-sync mode is different, switch to an alternative v-sync mode and switch back again. That should do it

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, 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’ 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.

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.

With high CPU usage, it may be running pretty hot, too, so we’ve put together a bunch of ways you can bring the CPU temperature down. Ransomware is also a big culprit in slowing down your PC and heating up your CPU, so here’s how to enable ransomware protection in Windows.