What I think is going on here has to do with lousy game engine implementations: with modern graphics APIs you have to take extra steps beyond relying on the swa

What I think is going on here has to do with lousy game engine implementations: with modern graphics APIs you have to take extra steps beyond relying on the swapchain to avoid running ahead of the GPU for multiple frames. It's not obvious and and I suspect a lot of games aren't that good at managing that. If the CPU runs ahead, you have a massive multi-frame input-to-screen lag that changes a lot with monitor FPS. But it's not the extra frames themselves that make the difference. It's just correcting for poor code.