The crazy thing is that even being powered by a lawn mower engine, he is by far at the top of his class... I almost wish there was a �diagnosis� to explain the huge differential in his scores.
This is my oldest dd. Her processing speed wasn't quite as low as your ds' but it was still on the lower end of average while working memory, perceptual reasoning, and verbal were all in the upper 90s (percentiles). She is 12 now and has skipped a grade and she is still near the top of her class.
As far as a diagnosis, we had an OT tell us that she had dyspraxia (a motor planning disorder), but I really am not too sure on that. I don't think that the problem is a mind - body disconnect so much as it just taking her mind longer to retrieve the info it has stored. Given that she wants to work in a field (marine mammology studying slow moving animals: sirenians -- lol), I think that there are places where her deeper, slower way of approaching things could be a benefit. I am fast and impatient on the other hand and that wouldn't lend itself as well to a field where one needs to stay still and observe things for a long time.