I was talking to my son about touch typing and whether he thought that would make writing easier for him. Yes, he says, for topics of interest.

"When I'm interested in something, my brain goes 100 billion times faster than my hand and when I'm not interested in something, my brain goes 100 million times slower than my hand."

I really really think that a large component of the writing issue maps to interest (lack thereof).

Still befuddled about the processing speed thing, especially how the different manifestations relate to one another:
1. Very low score on the WISC coding section (weak visual memory--and thus the need to look back and forth between the key and every sample that needs to be marked? But in regular everyday life, we don't see strong signs of weak visual memory).
2. Long time to come up with answers to some things--even when it's things that he enjoys doing and has very strong aptitude for (math).