How to fix
Lsalso.exe high CPU usage
on Windows

Hello. A couple of days earlier I noticed that my CPU usage has gone up and it causes my Windows computer to lag and crash. I opened the Task Manager and found that it was lsalso.exe that is causing high CPU usage. What is it and how do I fix it?

Recently, some users have encountered a problem with their Windows machines where lsalso.exe causes high CPU[ref en-1] usage. It is a more common problem than you may think. We previously wrote about Shell Infrastructure Host high CPU usage, Audio Endpoint Builder high CPU usage, Msedgewebview2.exe high CPU usage, and many others.

Lsalso.exe is associated with the Credential Guard and KeyGuard process and is developed by Microsoft. The process of this file typically runs in a secure environment called Virtual Secure Mode (VSM) as an Isolated User Mode (IUM) process. It is generally considered safe and essential, but can sometimes cause issues like high CPU usage within the system.

This is typically caused due to certain drivers and applications that attempt to load a Dynamic Link Library file (DLL) into the IUM process. This can cause the system to destabilize. In this guide, you will find 2 possible solutions to high CPU usage caused by lsalso.exe.

We recommend taking care of this as soon as possible as this can cause bugs, crashes, lagging issues, or even overheating which could lead to hardware malfunctions. You can also use a repair tool like [d1] to run a scan. This powerful software can fix various system errors, BSODs,[ref en-2] corrupted files, and registry[ref en-3] issues. Otherwise, follow the instructions below.

Solution 1. Use the Process of Elimination

Certain applications and drivers can load DLL into the IUM process, resulting in a higher CPU usage associated with lsalso.exe. You can try to eliminate the processes of these problematic applications and drivers and see if that fixes the issue.

• Type Task Manager in the search area and click Open
• Go to the Processes tab and locate the suspicious application
• Right-click on it and select End task

• Do the same with other potentially problematic applications
• See if the CPU usage has gone down
• If not, launch Device Manager and locate the drivers
• Right-click on them and choose Uninstall device from the context menu and see if that makes any difference in the high CPU usage caused by lsalso.exe

Solution 2. Check for Queued APCs

Microsoft has developed several Debugging Tools for Windows users that can help to check for problematic drivers. 

• Install the Windows Debugging (WinDbg) tool from the Windows Driver Kit

• Then, use NotMyFault.exe to generate a kernel memory dump during the spike
• To enable kernel memory, launch a Run dialog box by pressing Windows + R keys
• Type control system in the text field and hit Enter
• Click Advanced system settings

• Head over to the Advanced tab in the System Properties dialog box
• Click on the Settings button associated with Startup and Recovery
• Expand the drop-down menu for Write debugging information and choose Kernel memory dump

• Hit OK and note the Dump File location here
• Navigate to the Start menu and click on the Windows Kits entry
• Choose WinDbg(x64/x86) to proceed
• Click on File and select Symbol File Path
• Type https://msdl.microsoft.com/download/symbols for the Microsoft Symbol Server in the Symbol path section

• Click OK and access the File menu again
• Choose Open Crash Dump and browse the location you noted
• Click Open and type !apc in the command window and hit Enter
• Once the command is executed, look for <ProblemDriver>.sys under LsaIso.exe

• Contact your driver vendor now and then refer them to the Microsoft document for mitigation recommendations for Isolated User Mode (IUM)