How to fix rundll32.exe high CPU Usage in Windows 7 running Vanilla World of Warcraft

This guide is directed at users running World of Warcraft version 1.12.1 on Windows 7.

In some circumstances, “rundll32.exe” will use 100 percent of a CPU core. This is due to a fault in Microsoft’s GameUX. You will need to disable gameUX to fix this. This can be done by editing the registry.

Here’s how

Create a text file containing the following:

Windows Registry Editor Version 5.00

[HKEY_CLASSES_ROOT\Local Settings\Software\Microsoft\Windows\GameUX\ServiceLocation]
"Games"="127.0.0.1"

Then rename this file from *.txt to *.reg.

Run the .reg file.

Now you can play WoW

Going Back

If you ever want to undo these changes, then simply repeat the above steps with:

Windows Registry Editor Version 5.00

[HKEY_CLASSES_ROOT\Local Settings\Software\Microsoft\Windows\GameUX\ServiceLocation]
"Games"="https://games.metaservices.microsoft.com/games/SGamesWebService.asmx"