On August 31, Microsoft released a cumulative update for Windows 10 version 1903. It was the patch KB4512941, which is now known to be buggy. The issue it causes is a broken Search/Cortana. Yet another bug has emerged in the update KB4512941 that causes orange screenshots.
Last Friday, Microsoft released an optional cumulative update to users of Windows 10 version 1903 'May 2019 Update', which is build 18362.329. After installing the update, a lot of users have been reporting about high CPU usage by Cortana and SearchUI.exe. Microsoft has finally confirmed the issue and is about to ship a fix in an upcoming release.