Have you ever been the victim of an opponent hitting you from off screen? A mage casting Flamestrike? Arrows coming out of no where? Just because you don't see anyone on your screen does not mean you are alone. When running, the Ultima Online client can only approximate the position of another player chasing you. This has nothing to do with latency (lag), it has to do with the client just being unable to show you exactly where your opponent(s) are every fraction of a second. As you can see from this video, while one player sees no one the other appears to be running right behind.
