What is dllhost.exe Process and Why It Causes High CPU Load?

Process COM Surrogate (dllhost.exe) is a system process that allows to register COM objects (Component Object Model) in Windows 10, 8 or Windows 7.

For example, by default the icons for unsupported media formats won’t be displayed correctly in Windows 10. But once the user installs appropriate applications (like Photoshop, Corel Draw, photo viewer, codecs etc.), these application register their COM objects in the system and after that user can see an application thumbnail for related files in File Explorer.

The task that described above is not the only one for dllhost.exe process, but it’s one from basic. This can cause error COM Surrogate has stopped working or loads the CPU high. It’s important to mention that it’s normal situation when you see a few dllhost.exe running in the Task Manager.

dllhost exe

The original process’s system file is located in folder C:WindowsSystem32. You can’t delete dllhost.exe, but you have options that allows to fix issues related to this process.

Why dllhost.exe Loads CPU High and Causes COM Surrogate Has Stopped Working Error?

Most often high CPU or COM Surrogate error occurs while opening the specific folders in File Explorer, which contains videos or images in File Explorer (but that is not the only case when the issues appear).

So, the most common causes for the error are:

  1. Third-party application registered COM object incorrectly or they are not functioning properly (because of incompatibility with installed Windows version, old software etc.);
  2. Old codecs or the codecs that are not working properly (especially when the issues happening with displaying thumbnails in File Explorer);
  3. Sometimes the error can happen because of antivirus or malware, or due to the damage of the system files in Windows.

Using System Restore Points and Uninstallation of Applications/Codecs That Cause Issues

First of all, if the high CPU load and/or COM Surrogate error started appearing recently, you need to try to use System Restore Points on Windows 10. If you know for sure which freshly installed program started to cause issues, you need to delete them by going to Settings -> Apps on Windows 10.

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Tip. Even in case the error started appearing recently, first of all try to delete the installed codecs (for example, K-Lite Codec Pack) and then reboot your machine.

Damaged Files

In case dllhost.exe starts to cause high CPU load when opening some specific folder in the File Explorer – most likely, this folder contains damaged media file. There is a pretty simple solution on how to find such file (but it’s not 100% working):

  1. Run Resource Monitor (press Win+R, type in resmon and press Enter);
  2. Switch to CPU tab and check on dllhost.exe process, and then check if there are some media files in the list at section Associated modules. If you see such files – most likely, they are causing issues (you can try to delete them);

dllhost exe COM Surrogate

In case the issue with COM Surrogate occurs when opening folders which contains a specific type of files, most likely the problem can be caused by COM objects that are registered by some application and used to open the specific file type (you can check that by deleting this application and rebooting your machine after that).

Errors While Registering COM Objects

In case the methods above didn’t help, try to fix COM objects errors within Windows 10. It is not a guaranteed one, but sometimes it can help to fix the problems. Remember, that it also can do a harm to your system, so it’s recommended to a create System Recovery Point. Follow the instructions:

To fix such errors automatically we recommend you to use CCleaner:

  1. Run CCleaner, switch to Registry section and check on ActiveX and Class Issues. Now press Scan for issues;
  2. When the scan process finishes, click on Fix selected Issues;
    dllhost exe activex COM issue
  3. Confirm to back up changes to the registry and set the path to save the backup copy;
  4. After that reboot your machine.
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More Solutions on How to Fix COM Surrogate Error

In addition, you can use some of these notes to solve the problems with dllhost.exe:

  • Check your computer for malware using third-party utility (like AdwCleaner or your own antivirus);
  • In most cases dllhost.exe process issues are not related to a virus (but the problems can be caused by malware which is using COM Surrogate). First of all, check if dllhost.exe has a Microsoft signature. It’s important to check if the process file is located in C:WindowsSystem32 (you can check this by right clicking process in Task Manager and choose Open File Location).
    dllhost exe file locationIf you still have doubts – check your system for viruses;
  • Try to disable DEP for dllhost.exe (only for 32-bit systems!). To do this go to Control Panel -> System (or right click on This PC -> Properties), switch to Advanced system settings; now go to tab Advanced and in section Performance click on Settings;dllhost exe advanced settingsNow switch to tab Data Execution Prevention. Check on Turn on DEP for all programs and services except those I select, now press on Add button.dllhost exe DEPAt the next step set the path to file C:WindowsSystem32dllhost.exe. Apply the changes and reboot your machine.

That’s all, guys! We hope that now you know everything you needed about dllhost.exe process!


  1. Excelent article,

    The Damaged files step helped me a lot.

    I found that it was foxit reader who caused the problem.


    1. Yes, me too had this helped. The dllhost.exe-issue arose every time when I opened the video folder from PowerPoint. A media file created by VLC was not associated with the usual movie icon, but the VLC-logo-icon. Immediately, dllhost.exe starts and keeps “eternally” at 50% CPU (dual core system).

      For the sake of clarity: I treat this behaviour as a bug. Even a serious issue, since incompatible media files may at any time reside in folders that are queried by the user. Also when a media file cannot be associated the correct thumbnail image by the system, it is definitely problematic that dllhost.exe continues to hog CPU!

      (System: Windows 7 SP1)

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