What is service host SysMain high disk usage

Also known as Superfetch, SysMain is a native Windows service meant to optimize system performance. However, some users tend to stumble into serious problems whilst having SysMain turned on. The service can eat a lot of resources, increasing disk and CPU usage significantly. This, therefore, results in freezes, slowdowns, and many other things deteriorating the system. If you open the Task Manager, you will see the SysMain service on top of the list demanding a high number of resources. It is quite strange that something meant to improve your system does completely the opposite, but this is the reality of Windows OS. Sometimes SysMain can go awry leading to terminates and overheating issues. If not resolved in time, your hardware may suffer serious damage and end up dying eventually. Luckily, there is a solution to this. Simply follow the instructions listed below.

service host SysMain (Superfetch) high disk usage

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1. Stop SysMain service

The number one thing proposed on multiple forums is terminating the SysMain service to prevent high resource usage. In most cases, it works out great resolving the system pressure. Although SysMain is an integral part of Windows processes, you can disable it without consequences. Otherwise, it will continue holding your disk and CPU at unbearably high rates. Below, you can see different ways to disable the SysMain (Superfetch) service on your PC.

Disable SysMain using Windows Services

  1. Press Windows key + R together and type services.msc into the window.
  2. Open it up and search for SysMain or Superfetch service (the name depends on which Windows version you use).
  3. Once found, right-click on it and choose Properties.
  4. In General tab, click on Stop and then OK to save the changes.

Now you have disabled the SysMain service, which caused the previously-mentioned problems. Go to Task Manager and check if something has changed with the disk usage. If you did not manage to disable SysMain using this method, try two more alternatives down below.

Disable SysMain using Command Prompt

  1. Open Command Prompt by typing cmd into the searching box next to the Start Menu button.
  2. Right-click on Command Prompt and choose Run as administrator.
  3. Once the console has opened, insert this command and click Enter.

  4. sc stop "SysMain"
    sc config "SysMain" start=disabled

  5. At the end of the process, you should see ChangeServiceConfig Success at the bottom of console.

Disable SysMain using Registry Editor

  1. Press Windows key + R together as we did above and type regedit in the box.
  2. Click Yes if prompted by the User Account Control window.
  3. On the left side of Registry Editor, navigate to HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\SysMain.
  4. After clicking on SysMain, you will see a list of entries on the right pane.
  5. Find and right-click on Start, choose Modify, and type 4 in Value data.
  6. Click OK and close the window.

Overall, these 3 methods do exactly the same – disabling the SysMain (Superfetch) service on your computer. However, in case it does not solve the problem and appears back from time to time, we have some more methods discussed further below.

2. Install Pending Updates

Sometimes SysMain may not work correctly due to wrong or bugged configuration. The latest updates can deliver the fix and get the troublesome service back to working without the issues. Therefore, make sure you have the latest updates installed on your system. To do this:

  1. Press Windows key and I together to open Windows settings.
  2. Select Update & Security.
  3. Choose Windows Update on the left side and click Check for Updates (sometimes you will see the Download button meaning that an update is already found).
  4. Wait until Windows finishes the scan for new updates.
  5. Once found, install new updates and restart your PC.

3. Run a Clean Bootup

Often times third-parties applications that were downloaded from the web can conflict with your system and cause problems with certain services. Malware also falls in that category, so it would be reasonable to scan your PC for malicious presence. Clean bootup allows users to start their PCs with in-built apps and services to find out whether some secondary app prompts the issue. To launch your system with clean bootup, follow the steps below:

  1. Do Windows key + R combination and paste msconfig.
  2. Then in the opened window go to the Services tab located on top.
  3. Check the box next to Hide All Microsoft Services and click on the Disable all button.
  4. Now choose the General tab and select the Selective startup option. Make sure that the box is checked only next to the Load System Services.
  5. Click Apply and OK. Then reboot your PC.

Now you can check the disk usage as you are in the Clean Bootup mode. If there is no sign of pressure as it was before, then there is a chance that some third-party software is causing the issue. To find it out, you can delete the recently installed program or let specialized software do this on its own. One of the best anti-malware programs that show good results in detecting and combating malware/potentially unwanted programs is Malwarebytes Anti-Malware. You can download it via the button below.

Download Malwarebytes

4. Perform a System Restore

If you started seeing the error pop-up after running some changes or installing a program, you can select the date when everything worked fine through a restore point. Although this option is less likely to solve the issue of SySmain service, you can try it if nothing helps out. Just follow the steps below:

  1. Right-click on This PC and choose Properties.
  2. In the opened window, go to System Protection and click on System Restore.
  3. Then, click Next and choose the date you remember working without a problem. You can also click on Scan for affected programs, which will show what might be changed after running a restore.
  4. When done, click Next and start the System Restore.

5. Upgrade to an SSD

If you continue running into hot temperatures and overrated disk usage after testing all of the ways above, maybe there is a physical problem with the disk itself. Sometimes it can be damaged and does not process the memory as needed. Therefore, the solution lies in replacing the existing hard drive with a newer one. If you decide to do so, we recommend buying an SSD, since it is much better and faster than traditional HDD types. A new disk will potentially solve the issue and give some additional boost to the system.


Disk-related issues may be very annoying, especially if they prevent you from using the PC correctly. Disabling SysMain should remove the issue and decrease high levels of usage that slow down your system. The worst-case scenario is having physical problems with the hardware itself, which requires broader examination and actions to take. Despite this, we hope most of you found the right method and managed to fix the issue using our tutorial.

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