Possible things to try (preferably on Windows 11 with the latest updates and newest drivers): Prefer maximum performance and select the high-performance GPU for your graphic card. Clear NVIDIA shader caches (DXCache / GLCache) Reinstall DirectX 9 Run Supreme Commander in window mode, not just alt+tab it into the background Disable full screen optimizations for SC (Advanced) Some people, including myself a few years ago, have had good results with multi-monitor setups using dgVoodoo2. It may also help resolve your issue even on a single monitor: https://dege.freeweb.hu/dgVoodoo2/ReadmeGeneral/ If you have trouble understanding the suggestions, or AI does not help you out, just create a new support thread and 'imme a ping.