Windows 10 KB4512941 update causes 100% CPU core usage due to broken Cortana process

System Requirements

Low vs Ultra Screenshots

GPU Performance Chart

CPU List That Meet System Requirements

GPU List That Meet System Requirements


Windows 10

PC Demand


Rate this game

User Rating


There’s an optional new update for Windows 10 which it looks as if you should avoid at all costs. The KB4512941 update was released to the public after just a single day of testing in the Release Preview Ring, yet users have now discovered it causes very high CPU usage issues which will affect your PC performance.

The sky-high CPU usage comes courtesy of Cortana, Windows 10’s digital assistant who can use your voice to perform a variety of tasks. Helpful if you have a disability, but otherwise thoroughly useless for all but those with the laziest of digits. 

As of the W10 KB4512941 update, Cortana’s SearchUI.exe appears to be taking up 100% of a single core on a CPU at all times, while some users are reporting overall usage of just north of 40% for the process.. This will clearly cause some significant performance issues, particularly for users with lower core counts. If you have a quad-core CPU, for example, a quarter of your performance is being expended on a single background process.

To top it all off, this update breaks Cortana’s search function. Not only is it a tremendous performance drain but it doesn’t even work. 

“Cortana is consistently running above 35% CPU usage and 150 MB memory as reported by Task Manager, for at least one day now. Despite this fact, using the Search button next to the Start Menu pops up a dialog that will not display any items upon entering any search query, even after waiting for several minutes,” reports a user on Microsoft’s Feedback Hub.

In order to check which version of Windows 10 you are currently on, simply search for Windows Update in your search bar. Here you can click ‘View update history’ in order to see whether the KB4512941 update was installed. It is optional, for now, so it’ll only be installed if you specifically chose to. 

If you’re running an up-to-date version of Windows 10 and you haven’t installed KB4512941 then the Windows Update screen should look something like this:

If you have the update installed then it’s recommended you uninstall it for now. In the same Windows Update page, click ‘View update history’ and you’ll see an option to ‘Uninstall updates’ right at the top.