Although children often move at what seems like warp speed, they also need time to assimilate what they learn both from formal education and everyday life experiences. This is especially true for children who have autism. A recent study by Vanderbilt University and the University of Rochester found that children who have autism spectrum disorder perceive motion faster than their typically developing counterparts.
Here's a link to the study: http://www.medicaldaily.com/children-autism-see-motion-faster-245800
In her book "Animals In Translation", Temple Grandon hypothesizes that people with autism spectrum disorder (ASD) have a more difficult time filtering out sensory information than those without ASD. If this is the case, and no doubt different people have different experiences, it is vital for us to allow enough time for those in our lives with ASD to understand what their senses are telling them about the world, and to formulate a response.
Consider it a chance for all of us to take a breather.