53 isn’t slow for a 3rd autocross, that’s pretty good for 225 width tires and crappy Continentals! A lot a guys getting low 50’s have much wider tires than yours, and better rubber on them and way more experience.
Since this wasn’t a horsepower course and your lines look decent, the other advice is to gas earlier and brake harder! And get better tires (and wider if possible) when yours wear out.