While I've definitely had the slow audio processing i.e. I will often ask somebody to slow down and repeat what they've said, leaving them bewildered b/c English is my first language, I can't recall experiencing a pattern of slow visual processing if it is related to a singular factor, such as traffic lights changing or a scary movie reaction. However, where I DO have slow visual processing is where I'm asked to get an object, or notice an object, amidst a mass of other objects that an NT has pointed out to me. If somebody says "could you get the red bowl" for example, on a series of shelves, I will look around the shelf for it and the frustrated person will say "There!! THERE!!" I believe this has to do with difficulty in filtering out irrelevant elements, and not intuitively following the finger-pointing gesture to the desired object (the "non-verbal dyslexia" component of Aspergers).