You might want to read up on Visual Spatial learners as well. My son (6) is a deep thinker as well. His processing speed was in the normal range on his IQ. He placed very low on his "norming tests" (timed pencil and paper)in school but very high on the computer tests (comprehensive). The public school wants to put more emphasis on his speed (they call it fluency) even though he is extremely accurate when he takes his time to process. I have looked in LD but cannot find one that fits exactly. I have found the Visual spatial information fits to a "T". Here is the link to some VS articles.
http://www.homeschooldiner.com/specials/visual_spatial/main.html It is on the homeschooldiner website but it has a ton of great resources. Also scroll through to find out what happens if your son were to get a teacher who doesn't understand this and give credit for both knowledge and speed.
Feel free to PM me if you want more. Good luck.