I was working on my game when windows 10 needed to update, so I restarted my computer to update, and when I returned the preview of the game was unplayably laggy for some reason. This problem extends to .exe files of my game, but not any normal games run through steam. I know it's not an optimization problem because I made a simple game where a little guy jumps around and that's also incredibly laggy both in the game preview and in a .exe file.