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High CPU usage by Windows Module Installer Worker in Windows 8 or 8.1

  • Parallels Desktop 10 for Mac Home Edition
  • Parallels Desktop 9 for Mac Standard Edition
  • Parallels Desktop 8 for Mac Standard Edition


While running Windows 8.1, CPU usage is 180% in Activity Monitor:

At the same time Windows Module Installer Worker service is overloaded in Task Manager (click Start -> enter “task manager” into Search field -> click on View running processes with Task Manager -> Processes tab > sort by CPU):


In Windows 8 or 8.1 virtual machines sometimes CPU fan run very fast and make noise because Windows Module Installer Worker service occupies CPU more than 50%.


Change Windows update into manual mode:

  1. Open services.msc:
  2. Search "Windows module installer".
  3. Double click the "Windows module installer", and make it manual (right click on service -> choose Properties -> Startup type: manual). It is usually set Automatic.
  4. Search "Windows update".
  5. Double click the "Windows update", and make it manual.
  6. Open Control panel (right click at the lower left of the screen at the Windows logo. and then you can see control panel menu).
  7. Click "Windows update"
  8. In left you can see "Change settings".
  9. Change the setting into "Check for updates but let me choose whether to download and install them". It is usually set automatic.
  10. Reboot Windows virtual machine.

Important: Because Windows update is set manual, you must check regularly (weekly or monthly) Windows update by yourself.

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