The one thing that gives cats the edge over dogs is that they have a more streamlined build than they do, for the most part.
Cats also have an innate ability to be able to use their rear legs as a sort of spring-loaded contraption that allows them to take off running at a very high speed.
Cats also can thank their stamina. If a cat is healthy and well-built, then it will have endurance, allowing it to run quickly for a fairly large distance.
Cats also have incredibly good reflexes usually. Most times, you cannot sneak up on a cat without them seeing you or sensing you.
Cats rely on their senses and instincts to survive, and if something tickles their senses wrong, their first instinct is to run, and they can run fast.
For more information about cats and other things they do instinctually, follow this link to the website of the veterinary clinic Willis.