Windows Processors Eating Excessive CPU – Diagnostic Policy Service and WSAPPX

by | Sep 21, 2025 | Misc | 0 comments

The “Service Host: Diagnostic Policy Service” can consume high CPU for several reasons, primarily related to the creation and growth of system diagnostic logs in Windows. The Diagnostic Policy Service (DPS) runs in the background to detect and troubleshoot Windows component issues, but if the log file (typically SRUDB.dat located in %WinDir%\System32\sru) becomes very large or corrupted, it can cause the service to keep the CPU busy excessively.

Common causes and fixes include:

  • Large or corrupted log file (SRUDB.dat): The DPS continuously creates logs in this file. If it grows excessively, it can cause high CPU usage. Deleting this file after stopping the service often resolves the issue. Windows will recreate a new log file when restarted.
  • Power plan settings: For laptops, some default power plans or driver issues might trigger DPS to spike CPU usage. Changing the power plan to “Maximum Performance” can help reduce the load.
  • Event Viewer logs bloat: Excessively large event logs can increase system overhead. Clearing Windows event logs can also mitigate CPU spikes due to DPS.
  • Stopping and restarting the service: Temporarily stopping the Diagnostic Policy Service via the Services console and then starting it again can clear temporary problems with the service.
  • System performance impact: When affected, you might notice slowdowns, high CPU percentages (sometimes 25-30%), or excessive fan noise due to high CPU frequency sustained by DPS.

Here is a summary of practical steps to fix it:

  1. Open Task Manager, end the “Service Host: Diagnostic Policy Service” task.
  2. Open Services (services.msc), stop the Diagnostic Policy Service.
  3. Navigate to %WinDir%\System32\sru and delete SRUDB.dat file.
  4. Change power plan settings to “Maximum Performance” if applicable.
  5. Clear Windows Event Viewer logs (Application, Security, Setup, System).
  6. Restart the Diagnostic Policy Service and your computer.

These steps have proven effective in resolving high CPU usage related to this service.

If the problem persists, it may be helpful to check for system updates, run system file checks (SFC/DISM), or investigate if a recent update or driver may be triggering the issue.

The WSAPPX service in Windows can consume around 30% CPU because it is responsible for managing the installation, update, and licensing of Microsoft Store apps and Universal Windows Platform (UWP) apps. High CPU usage typically occurs when:

  • You are installing or updating apps from the Microsoft Store.
  • Apps are updating automatically in the background.
  • There is heavy activity related to the Windows Store infrastructure, such as app deployment or license verification.

WSAPPX includes sub-services like AppX Deployment Service (AppXSVC) and Client License Service, which handle these tasks and can sometimes use significant CPU resources temporarily while working.

Common causes of persistent high CPU usage by WSAPPX include:

  • Continuous background app updates or installations.
  • Corrupted Windows Store license database.
  • System or Store app errors causing the service to get stuck processing.
  • Possible malware masquerading as WSAPPX (less common).

Some practical solutions to reduce CPU usage by WSAPPX are:

  • Disable Windows Store if you do not use it (via Local Group Policy or Registry Editor).
  • Extend virtual memory (paging file size).
  • Check and repair disk errors.
  • Update device drivers.
  • Clean boot your system to identify interfering apps.
  • Scan for malware.
  • If the Windows Store license database is corrupted, repairing or resetting the Store cache may help.

Note that disabling WSAPPX or Windows Store will stop installing or updating Store apps.

If WSAPPX is consistently using high CPU without activity related to app installs or updates, it may indicate a problem needing deeper troubleshooting or system repair.