I took a creative writing class at University (mostly on a whim). One of the stories I proof-read was a novel about this idea. That the universe didn't tick at a uniform rate and there were people who could "tick" faster or slow. Of course, you run into all sorts of people with breathing and moving through very hard air. The core tenet of the book was that the clock domains of the universe were drifting apart at an accelerated rate and the protagonists were trying to stop it. It was an interesting concept and a fun short story.