I'm thinking that what we call time slowing down is really a person in an adrenaline mind rush, speed thinking if you will. All of a sudden the mind goes into overdrive, accesses the situation in record time, and the mind and body react.
In sports, we often talk about time slowing down. When a quarterback sees a 300 pound lineman racing towards him, he quickly scans the field for a pass receiver, and dumps the ball off - if he's lucky. He gets creamed if time doesn't slow down enough.
Baseball players often see time slowing down enough to identity a 95 mph fastball, swing and make contact; or identify an 85 mph curve ball and determine if it's going to be a ball or strike. It is commonly said that time slows down for the best athletes.