Rat snakes are usually good at gulping down food quickly- most have a wide gape, which helps, along with motivation. The Beauty rat snakes have a proportionally longer face that means they're "born to gulp".
My slowest eater is my rosy boa. I love to feed my rat snakes- they don't mess around. If you enjoy snakes that eat fast, you'd also like the Pituophis family- bull, gopher & pine snakes. Like rat snakes, they're active hunters that eat on the fly.