Yeah, but there's still a latency penalty, because X_1, X_2, X_3 won't respond to player input, so your effective latency is still that of your 'real' FPS, and

Yeah, but there's still a latency penalty, because X_1, X_2, X_3 won't respond to player input, so your effective latency is still that of your 'real' FPS, and that's lower than without because the frame gen takes a good fraction of GPU resources.