Sonic Mania Time Attack Studiopolis Zone act 1(Tails and Knuckles) with glitched v-sync and windowed

why v-sync glitching and game too smooth, but so annoying? I losing rings every time when I trying to be best! I used optical flow and speed up of Knuckles footage for best experience. Why games are too unoptimised for higher fps? I have 60 hz monitor, whatever.. recorded from captura with ffmpeg #vsyncoff #glitched #captura