What is Service Host SysMain (Superfetch) and How to Disable It?

Service Host Sysmain is a Windows system process that has gone by various names over the years. In Windows XP it was known as Prefetch. In Windows Vista, it was known as Superfetch. It received the current Sysmain moniker in the latest versions of Windows 10. Regardless of what name was given to it, Sysmain/Superfetch/Prefetch, its purpose has been the same – to increase Windows performance by preloading frequently used applications into RAM before you need to use them. In this post, we will find out what it is and how you can disable it if needed.

Service Host SysMain (Superfetch): All You Need to Know

How does Service Host Sysmain (Superfetch) work?

In the latest versions of Windows 10, the Superfetch service now appears under the name SysMain. In Task Manager, it appears as Service Host: SysMain.

If you are running an older version of Windows 10 or any version of Windows 7 or 8, this will show up in Task Manager as Service Host: Superfetch.

This service runs in the background (with very little CPU power) and analyzes the amount of RAM you are using and the applications you run most frequently.

Any application that the service recognizes as “frequently used” will begin to preload the application into RAM. This way, the next time you run the application, it will start up much faster.

You may be concerned that this means that Sysmain (Superfetch) is consuming all of your RAM, but it is not. The service focuses on preloading applications in unused RAM. This is not recorded as memory consumed. You will see this if you open the Task Manager in the Processes tab and look at your Memory usage.

Although Sysmain (Superfetch) is consuming all the unused RAM with preloaded applications, the consumed RAM usage still does not show 100%.

This is because Sysmain (Superfetch) is running in the background and will free up any unused RAM you are using whenever you need to use that memory for other active tasks.

Should you stop running Service Host Sysmain?

Generally, it is not necessary to stop the execution of Service Host Sysmain. It uses a miniscule amount of CPU and only uses unused RAM. All of this goes unnoticed by the general user.

However, there have been some reports on Microsoft user forums that sometimes the Superfetch (Sysmain) process actually causes performance issues. Some of these reported issues include:

  • Constant 100% disk utilization.
  • Overheating causing system shutdown.
  • Slow boot time when you start your computer.
  • On weak hardware, Superfetch could use more CPU and RAM than you’d like.
  • It is known to cause performance issues when gaming.

The most common problem people report is the 100% disk utilization problem. If it’s the same with you, disabling Superfetch or Sysmain may solve the problem.

Since Sysmain (Superfetch) is just a system optimization feature, it will not harm Windows by stopping the service. However, you may find that your favorite applications may take a little longer than usual to start.

How to disable Service Host Sysmain (Superfetch) in Windows 10

Is it safe to disable Service Host Sysmain (Superfetch)?

If you are not experiencing performance or other issues, it is a good idea to leave Superfetch (Sysmain) running. It’s a useful process that significantly reduces the time it takes you to start programs that you use frequently.

However, if you are experiencing high hard disk utilization, constant memory problems, or poor performance in general, you can try disabling Sysmain to see if it solves the problem. If so, leave the service disabled. If not, turn it back on and continue troubleshooting.

How to disable Service Host Sysmain (Superfetch) in Windows 10:

  1. Select the Start menu, type services and select the Services application. You can also press Windows + R, type services.msc and press Enter.
  2. In the Services application, scroll down to SysMain, right-click the service, and select Stop. If you are running an older version of Windows, right-click the SuperFetch service and select Stop.
  1. You should now prevent the service from restarting when Windows starts. Once the service is stopped, right-click on the service again and select Properties.
  2. In the Startup type drop-down menu, select Disabled.

Now the Service Host SysMain (Superfetch) service is permanently disabled and will not restart the next time you start your computer.

Disable with Registry Editor

An alternative to using Task Manager to disable Service Host Sysmain in Windows 10 is to use Registry Editor.

Before you start doing anything inside the registry, make sure to take a full registry backup, in case something goes wrong.

When you are ready:

  1. Select the Start menu, type regedit, and select the Registry Editor application.
  2. In the Registry Editor, navigate to HKEY_LOCAL_MACHINE> SYSTEM> CurrentControlSet> Control> Session Manager> MemoryManagement> PrefetchParameters.
  1. In this section, you should see a key called EnableSuperfetch. Right-click on this key and select Modify.
  2. In the Edit DWORD window that appears, change the Value Data field to 0 and select Okay.

You can close the Registry Editor when you are done.

This registry entry will disable the Service Host SysMain (Superfetch) service on your system. However, you may need to restart your Windows machine before these registry settings take effect.

How to enable or disable Service Host SysMain (Superfetch) with command prompt

If you prefer to work with the command prompt, there are a few simple commands you can use to enable or disable the Sysmain (Superfetch) service.

First, open the command prompt in administrator mode and then use the following commands:

  • Enable: sc config “SysMain” start = auto & sc start “SysMain”
  • Disable: sc stop “SysMain” & sc config “SysMain” start = disabled

Note: If you are using an older version of Windows, please replace “SysMain” with “SuperFetch” in the above commands.

If you prefer PowerShell, open it with administrator rights and use the following commands:

  • Enable: Set-Service -Name “SysMain” -StartupType Automatic -Running Status
  • Disable: Stop-Service -Force -Name “SysMain”; Set-Service -Name “SysMain” -StartupType

This approach can be much faster and easier than clicking the Task Manager or the Windows registry.

What to do if the problem still persists?

If disabling Service Host SysMain (SuperFetch) doesn’t solve your problem, then something else may be the source of the problem.

If you still have 100% disk usage, you may need to upgrade to a larger hard drive or choose to upgrade to an SSD drive. SSDs are very affordable now and have much higher data transfer rates than traditional hard drives.

If you are having CPU utilization issues, explore other CPU troubleshooting tips to identify the culprit that is consuming all of your CPU resources.

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