When Zen monks are completing a task, why are they doing it very quickly?

Recently, I watched a documentary about zen philosophy and what it is like to be zen monk on a daily basis and I noticed that in the documentary the zen monks always looked like they were in a hurry. For example, in the documentary we see the monks "rushing" to sleep. Another instance in the documentary is when one monk is waking up the other monks, we see that he is running. The question is: is there a reason behind the speed? Thanks