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

Written by Jon Sutton on Tue, Sep 3, 2019 9:53 AM
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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.

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02:32 Sep-05-2019

Cortana is suffering from Rampancy.

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17:15 Sep-04-2019

I have cortana disabled and it's still busted. One core is locked at 100% and the start menu search doesn't work. Uninstalled immediately.

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13:32 Sep-04-2019

they break something with each cumulative update every time

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junior admin badge
08:06 Sep-04-2019

Solution disable Cortana.

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17:16 Sep-04-2019

Nope, still broken even with Cortana disabled.

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junior admin badge
07:09 Sep-07-2019

Damn, that's ed up.
Another one of MS
ups.
And MS wonders why ppl aren't keen on updating...

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05:43 Sep-04-2019

Everyone. BACK TO 1809


Even better with LTSC

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04:59 Sep-04-2019

That windows 10 rating lol: 6.66

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23:18 Sep-03-2019

with this latest windows update it seems you'll literally need to open a window after your CPU gets cooked! all seriousness did QA kind of miss this? or was it just one of those we need it out now kind of updates?

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17:21 Sep-03-2019

I've heard about this issue, and how it was affecting some people who had also disabled Cortana, but I got this update and I'm not experiencing any problems. I don't use Cortana, and have basically disabled it (without going through the registry), and disabled the button on the Start Menu search bar. My searchui.exe is listed as 'suspended' right now. Some others here were speculating if you have to actually use Cortana or search with it first before encountering this issue, and I'm thinking the same thing.

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16:52 Sep-03-2019

Ah sh*t here we go again...

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16:39 Sep-03-2019

I don't get it. Why would a user use cortana for?

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13:34 Sep-04-2019

god knows .. never used or need cortana. its just another garbage feature

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16:33 Sep-03-2019

Guess I am really lucky at avoiding update issues. I always have my windows 10 updated and drivers up to date and never had a problem. Didn t have a single issue for years on windows 10 it is currently my favorite os.

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16:17 Sep-03-2019

i just delete the regedit key(Search) to fix the problem.
(HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Search)

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15:54 Sep-03-2019

"Do you know that you can still upgrade to Windows 10 for free?"
@Jon Sutton

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14:47 Sep-03-2019

This is why i'm still on 1809, i will maybe update when 1909 is released.

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11:21 Sep-03-2019

Oh look, another broken mess of an update by Microsoft. In other news, water is wet.

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10:28 Sep-03-2019

Had this update for three days now no issues...maybe you need to launch cortana to see this bug or something but i dont have it lol so im keeping the update unless i spot this bug but good to know.

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10:58 Sep-03-2019

Same as you. Updated windows but i don't have this bug. I disabled cortana long time ago because i don't use it . Will keep this update as long i don't see some problems !

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11:17 Sep-03-2019

Same.

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11:49 Sep-03-2019

The first thing I always do when I install Windows is disable Cortana. Completely useless feature. I've not come up to many problems so far with W10.

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10:27 Sep-03-2019

I wouldn't know because Server 2019 comes with all the good of Windows 10 and none of the useless garbage. ;)
Think Windows 7 features but with DX12 and whatever else got improved since then.
You can even turn down telemetry settings to security and put updates on manual. :)

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10:13 Sep-03-2019

It's like it impossible for Microsoft to not f**ked up any update nowadays

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10:13 Sep-03-2019

Why does anyone update windows 10 anymore? If it isn't broken don't fix it...else it will be broken lol

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