Service Host Sysmain (Superfetch) High Disk Usage Fixed on Windows

If your computer is suddenly having performance issues, the most common culprit is having high disk usage, which is when an application or process begins eating up your hard drive disk’s resources. This can happen for a number of reasons, but one reason that is reported a lot is due to the service host sysmain program, also known as Superfetch. In this detailed guide, we will run through what service host sysmain is, why it might be causing high disk usage, whether it’s a virus, and if it is safe to disable it. We will then provide troubleshooting steps to solve the service host sysmain high disk usage issue on Windows 10 /11. 

What is Service Host Sysmain, also known as Superfetch? 

The service host sysmain, formally known as Superfetch, is a built-in bundle of system processes introduced back in Windows Vista in 2007. Before Vista, it was known as prefetch in Windows XP. Its main purpose is to improve your system over time by optimizing your startup applications. It does this by analyzing your most commonly used programs and then pre-loading them into your computer’s memory so they can start faster. This service is important for overall system performance but can sometimes cause high disk usage. 

When the service host sysmain is the culprit of high disk usage, you will see it running in your task manager. If you’re not sure how to open your task manager, you can press Ctrl + Shift + Esc on your keyboard, or you can search for it in your start menu. Once you have your task manager open, click on the “Processes” tab and then look for service host sysmain in the list of processes. If the service host sysmain is causing high disk usage, you will see it using a large amount of your hard drive’s resources. It will likely be near the top of the list, using anywhere from 50-100% of your disk. 

Why does Service Host Sysmain have high disk usage?

While service host sysmain sounds like a great idea in theory, in practice, it doesn’t always work that well and can often lead to high disk usage on your computer. Now that we know what it is and how to spot it, let’s discuss some of the reasons behind why it might be causing high disk usage.

• One reason service host sysmain could be spiking your disk usage is due to a driver issue. If you have any corrupted or outdated drivers, service host sysmain will try to fix them, which can lead to high disk usage. You can check if this is the case by opening your device manager and then looking for any devices with a yellow exclamation mark next to them. If you see any, try updating the drivers.
• Another potential reason service host sysmain high disk usage is due to a pending Windows update. Service host sysmain will often run when there is a Windows update that needs to be installed. This is because it is responsible for pre-loading some of the files needed for the update. Once the update is installed, service host sysmain high disk usage should go back down to its normal levels.
• Service host sysmain might have high disk usage due to a virus or malware infection. If your computer is infected, service host sysmain will try to run the virus scan, which can lead to high disk usage. If you think your computer might be infected, you can run a virus scan with your antivirus software.
• Service host sysmain has been known to get “stuck” in a loop where it continuously tries to load files into your RAM, even when they are not needed, which can lead to your hard drive being overworked and causing performance issues.

Is Service Host Sysmain (Superfetch) a virus? 

Many people think service host sysmain is a virus because it can cause high disk usage, but it’s not a virus. It is a legitimate system process that is important for your computer’s performance. That being said, service host sysmain can be exploited by viruses and malware to cause high disk usage, so it’s important to run a virus scan if you think your computer might be infected. 

Is it safe to disable Service Host Sysmain, and what happens if I do?

It is safe to disable the service host sysmain (Superfetch) process, but it’s not recommended since this is a critical process that helps cut down on user work and automates many startup processes. 

If you do decide to disable it, you will see an immediate improvement in your system’s performance, but this is only temporary. Rather, applications that you typically use all the time will actually run slower over time because they aren’t being preloaded into the computer’s memory, causing your computer to do more work in loading up the program every time you want to use it. 

How to fix Service Host Sysmain (Superfetch) high disk usage

If the service host sysmain (Superfetch) process shows high disk usage, there are a few things you can do to fix the problem. While the first inclination is typically to disable it, it is recommended that you try some other troubleshooting methods first, as disabling sysmain should ideally only be used temporarily. We will walk you through how to disable it down below. 

1. Scan your system for viruses.

If service host sysmain has high resource utilization, one potential reason could be that your computer is infected with a virus or malware. In this case, service host sysmain will be trying to run a virus scan, which can lead to high disk usage. To check if your computer is infected, you can run a virus scan with your antivirus software. If you don’t have any antivirus software installed, we recommend using Windows Defender, which is a free antivirus program that comes with Windows.

1. In your computer’s search (start) menu, type in “Windows Security”.
2. Click into the Windows Security App. 
3. On the left-hand side panel, select Virus and threat protection from the list. 

4. From here, click on Scan Options, and choose Full Scan from the list.
5. Then hit the Scan now button. 
6. Wait until the scan is complete to see if any viruses or malware were found. If there are, use Windows Defender to remove them and then reboot your computer. 

If this was the cause of the service host sysmain high disk usage, then removing the unwanted malware will stop service host sysmain from constantly trying to run scans, thus lowering the disk usage percentage. 

2. Make sure Windows is up-to-date.

Another potential reason service host sysmain could be high is due to a pending Windows update. Service host sysmain will often run when there is an update that needs to be installed. Once the update is installed, service host sysmain should go back to normal. To check for updates:

1. You should go to Settings > Update & Security > Windows Update.
2. Then click the Check For Updates button. 

3. Use SFC Scan to Fix Corrupted Files.

If service host sysmain still consumes high disk resources, it could be due to corrupted system files on your computer. To fix these corrupted files, you can use the built-in SFC utility.

1. In your computer’s search (start) menu, type in “CMD” (Command Prompt) and right-click on the Command Prompt app to open it as an administrator.
2. In the CMD prompt window, type in “SFC /Scannow” and hit Enter.
3. Allow the scan to run through and automatically repair any corrupted or missing files. Keep in mind that this scan may take several minutes to complete.
4. Once the scan has been successfully completed, restart your computer, and see if the service host sysmain’s disk utilization has been reduced.

Note: If you run into an SFC /Scannow error when starting the scan, don’t worry. We have written dedicated articles on what to do if SFC scannow is not working, including:

• Windows Resource Protection Could Not Perform The Requested Operation
• Windows resource protection could not start the repair service

4. Disable Backup Intelligent Transfer Service (Windows 11).

If service host sysmain has high disk usage on your Windows 11 computer, one potential fix could be to disable the Backup Intelligent Transfer Service. This is the program responsible for assisting your computer in data transfers between foreground or background downloads and uploads between your device and the Microsoft servers. It can pause and resume data transfers automatically. If you do try this step, ONLY disable this temporarily, as it can cause major interruptions in the automatic Windows updates.

1. Press the Windows key + R on your keyboard simultaneously.
2. In the Run Dialogue box that pops up, type in “services.msc” and press Enter.
3. In the services list, find the Background Intelligent Transfer Service in the list and select it. 
4. Right-click on it and choose Properties.
5. Under the service status section in the General Tab, choose Stop.
6. Hit Apply and Exit. 

5. Disable automatic updates.

Another potential fix for service host sysmain high disk usage could be to disable automatic updates. This is a service that automatically downloads and installs Windows updates in the background. If this service is running, it can lead to high disk usage. However, we only recommend disabling this service temporarily because it’s important to keep your computer up-to-date with the latest security patches.

1. Press the Windows key + R on your keyboard simultaneously.
2. In the Run Dialogue box that pops up, type in “services.msc”
3. Then hit Enter.
4. In the services list, find the Windows Update service.
5. Right-click on it and choose Properties.
6. Under the service status section in the General Tab, choose Stop.
7. Hit Apply and Exit. 

6. Perform a Clean Boot.

If the service host sysmain resource utilization is still high after trying all of the above steps, you can try performing a clean boot. This will start Windows with a minimal set of drivers and startup programs so that you can determine if one of these programs is causing service host sysmain to use high disk usage.

1. In your computer’s search (start) menu, type in “System Configuration”. 
2. Under the general tab, choose the selective startup option. 
3. Then uncheck the load startup items option and hit Okay. 

This will restart your computer in selective startup mode. Once your computer has restarted, check to see if the service host sysmain is still high in the task manager. If it is, you can try disabling individual startup programs one by one to determine which program is causing the service host sysmain high disk usage. 

7. Consider upgrading your hard drive disk.

One potential long-term solution to service host sysmain’s high disk usage could be to upgrade your hard drive disk. If you have an older hard drive, it might be running slowly, which can lead to high disk usage. Consider upgrading to a Solid State Drive (SSD), which is much faster than a traditional hard drive. This will help improve your computer’s overall performance and speed up service host sysmain. 

How to disable Service Host Sysmain (Superfetch)

If you’ve tried all of the above solutions and service host sysmain still shows up at the top of the task manager disk utilization list, you can try disabling the service temporarily. This will stop it from running and using up your computer’s resources. However, keep in mind that this is only a temporary fix, and service host sysmain will start running again when you restart your computer. The two easiest ways to disable service host sysmain are using the Command Prompt window and the Services window via the Run dialogue box. 

Disabling Service Host Sysmain with Command Prompt

1. In your computer’s search (start) menu, type in “CMD”.
2. Right-click on the application and run as administrator.
3. In the Command Prompt window, type in the following command and press Enter:
   sc stop “SysMain” & sc config “SysMain” start=disabled
4. This should give you a notification that the configuration for sysmain was successful in disabling. 
5. Close the Command Prompt and see if the high disk usage has been eliminated.

Disabling Service Host Sysmain with Windows Services

1. Press your Windows key + R simultaneously. 
2. Type in “services.msc” and hit Enter.
3. Find SysMain in the new window that pops open.
4. Select it and right-click it to access Properties. 
5. In the properties menu, find the services status section.
6. Hit Stop. 
7. Then under the startup type drop-down menu, choose Disable. 
8. Hit Apply, and Okay. 

You can also disable service host sysmain through the registry editor, but we only recommend this to those who know exactly what they are doing as a wrong value change in the registry editor can compromise your computer’s performance and cause you to lose valuable data. 

Conclusion

We hope this guide has helped you fix service host sysmain’s high disk usage on your Windows computer. If it has, comment below and let us know which method worked for you.

If you run into similar issues with the related Service Host: Local System service, we have a separate article on how to remediate high CPU or high disk usage of Service Host: Local System.