https://wccftech.com/latest-windows-10-update-causes-huge-cpu-spikes/

Windows 10 May 2019 Update aka version 1903 received an update last week, bringing fixes to a number of known issues. Build 18362.329 (KB4512941) finally brought fixes to Windows Sandbox and the Visual Basic problems. It now appears that the update may have brought at least one problem too.

Users have been experiencing CPU usage spikes after installing this optional cumulative. The problem seems to be associated with Cortana and its SearchUI.exe process that is reportedly using 30-40% of the CPU and 150-200MB of memory.