Think about doing an escort quest where the NPC walks at 25% your speed and how irritating it is to have to keep waiting for them. Now imagine the NPC moves at %0.0025 or your speed instead. If he ever wants to travel with any companions, this might be more to protect his sanity than anything.
Most people are able to do this. Some have an on/off switch that stays jammed in the on position most of the time.