I have always been a fast walker as many here describe. And unfortunately one of my biggest aspie traits is the inability to communicate without exercising gruelling detail. Below is a synopsis of what I would want to contribute to this thread, otherwise it would be a book.
I recall seeing something about the buddist perspective on fast walking. The gist came down to circumstance of anxiety and a lack of present mindedness. I think this could be fundamentally true. "The man who walks fast does not enjoy the walking, and rather scurries about like a frightened mouse". I am pretty sure this is how it is seen by any outside observers.
I think one attribute that is profoundly prevalent in anxiety is forward thinking, where when anxious one tends to think about escaping the present moment by idealizing a future moment (i.e. right now sucks, so I am going to idealize some future moment that will be better to dampen how much right now sucks). The side effect of this forward thinking is not operating to improve the suckiness of the present moment, which leads to a circumstance that by the time we reach that future moment 'now' still sucks, so there then continues to be a fixation on some other future moment, ad infintum. Fast walking could be and likely is an affect of this subconsious thought process.
This is at odds of course of mine and others conception of the efficiency of fast walking. I do a lot of walking day to day, if I didn't walk fast I would lose MINUTES of my precious time! And its healthier to walk fast, more like exercise! How silly in retrospect.
I don't know if I could ever preferrentially get myself to walk slower. Something I heard that resonates with me is the fact that nature operates predominantly at a slow pace. Rapid pace is typically only existent in the presense of some stress or anxiety, the fight or flight reflex. It therefore becomes a practice in meditation to operate at a slow pace and be present minded in the action of now and do it well, even when walking, and not be fixated on or enchroached upon by the future moment. The purpose to to enjoy the present moment, rather than walking quickly to do something so that something can be over sooner. On the flip side it is possible that by artifically increasing pace, there is an unseen subconsious/physiological impact by becoming inharmonious with the natural pace of the world.
If we were picking berries it wouldn't be so hard, but as I work between two school campuses serving 100 staff, 1500 students, 500 computers and half a dozen servers its hard to draw a parallel to the natural, pleasant slow pace of Nature.