[ChuckElias]

Yes, there are good officials who are slow. But it's not just about "keeping up", although I think that's important. An official who is not physically fit is going to get physically tired more quickly. It's a pretty well-established fact that physical fatigue corresponds to mental fatigue. If an official tires quickly, s/he will not have the same level of judgment as an official who is physically fit.

If you want to stay mentally sharp deeper into your games, get yourself physically fit as well.