does this help ?
Windows 10 KB4482887 Cumulative Update Causing Major Stuttering in Games
Microsoft also confirmed the problem when it added a new known issue to the list available on the KB4482887 Cumulative Update page:
Microsoft's solution: uninstall the KB4482887 update
Until that happens, Microsoft recommends that gamers experiencing FPS drops in some games and overall performance issues related to mouse movement to uninstall the February Cumulative Update for Windows 10 Version 1809: "As a short-term resolution, users can uninstall KB4482887 to regain performance.
I'm on Windows 7 (64bit) so the problem must be somewhere else (or there is two different problems).