'Service Host SysMain' High CPU Usage

With the release of Windows 10 update 1809, Microsoft removed the Superfetch service and substituted it with SysMain. The goal of both services is one and the same - to optimize the performance of the system by preloading certain often-used applications. Users can then enjoy reduced startup times for those applications. The main difference between Superfetch and SysMain is in the methodology. To achieve reduced load times, Superfetch utilizes a paging file on the hard disk that acts as virtual memory and an extension to the system's RAM. The implementation wasn't without problems and many users suffered high disk usage and system slowdowns.

SysMain offers a far better service. Instead of moving data to a paging file, it compresses it allowing the PC to maintain optimal performance even under hard load. While SysMain is superior to Superfetch, it is not without issues. Users can still be plagued by high disk usage. In addition, the service also could take up a significant portion of the CPU's resources. In these cases, a service that is designed to make the system faster leads to the exact opposite outcome. The SysMain service comes enabled by default so users will have to disable it manually. There are several different methods but two of the easiest are described below.

Stop SysMain via Windows Services Manager

1. Press Windows + R on your keyboard to open the Run dialog box.
2. Type services.msc and click 'Ok.'
3. Locate 'SysMain' in the list of services.
4. Right-click it.
5. Choose 'Properties.'
6. Find the 'Stop' button located under the 'Serice status' section and click it.
7. Now, set the 'Startup type' to 'Disabled' via the drop-down menu.
8. All that is left is to click 'Apply' and then 'OK' to save the changes.

Disable SysMain via Command Prompt

1. Type command prompt in the search field on the Taskbar.
2. Either right-click the top result and choose 'Run as administrator' or pick 'Run as administrator' from the options listed on the right.
3. Now that we have an elevated Command Prompt window, type the sc stop “SysMain” & sc config “SysMain” start=disabled command in it and press 'Enter' on your keyboard.
4. Close the Command Prompt window and check if the disk and CPU usage has returned to normal.