After installing KB4512941's cumulative update for Windows 10 v1903 last week, some users report that the SearchUI.exe process for Cortana shows high CPU usage and spikes.
This is caused by a bug release of Cortana in this version, which seems to have problems when users have disabled the ability to send local searches to Bing, whether through registry or group policy. If this feature is disabled, Cortana will increase a lot of processor and Windows Search may show blank search results.
You can see an example of Cortana using 40% of the processor in the image below by a Reddit user. [1
To fix this, Windows 10 users have three options; activate BingSearch, replace the Cortana Cache folder with an older version, or uninstall the update.
While some cumulative updates introduce new bugs in Windows 10, they fix many larger amount, so it is not recommended to uninstall it unless you do
Instead, you can temporarily activate BingSearch until this problem is resolved by setting the value BingSearchEnabled to 1 under HKEY_CURRENT_USER Software Microsoft Microsoft Microsoft Microsoft Windows CurrentVersion Search Registry key.
[HKEY_CURRENT_USERSoftwareMicrosoftWindowsCurrentVersionSearch] "BingSearchEnabled" = 1
Gunter Borncity.com native also mentioned that some users have reported that they have succeeded in fixing this problem by replacing with: Windows SystemApps Microsoft .Windows. Cortana_cw5n1h2txyewy cache folder with a copy of a previous version of Windows found in C: Windows.old.
Other users on Reddit have had a similar experience repairing it this way, but it does not allow Windows Search.
"I was able to troubleshoot the processor by copying the cache folder from the archive to windows.old. However, my local search is no longer working. Any ideas on how to make it work again and still have fixed CPU usage ? "
Finally, Rodin also mentions that you can enable or disable the policy Do not allow network searching according to Computer Configuration Policies Administrative Templates Windows Components Search to solve the problem.
Microsoft has not currently acknowledged these errors in its KB4512941 Support Bulletin:
"Microsoft does not currently know any issues with this update."
H / T Windowslatest.com