I am not sure if there is any correlation between processing speed and ADHD. MY DS9 is gifted and has adhd. I think you can be fast and not get things right or you can be fast and process things quickly and get things right. If that makes sense. Over all my son is fast and gets things right. However, his standardized testing isn't always consistant. They are always good but some are really good and some are just good if that makes sense. I think this is because of his ADHD not because he isn't processing well. Who knows its always a quesss. Below is a something I pulled from an ADHD / gifted book that I thought was interesting.
One characteristic of ADHD that does not have a counterpart in children who are gifted is variability of task performance. In almost every setting, children with ADHD tend to be highly inconsistent in the quality of their performance (i.e., grades, chores) and the amount of time used to accomplish tasks (Barkley, 1990). Children who are gifted routinely maintain consistent efforts and high grades in classes when they like the teacher and are intellectually challenged, although they may resist some aspects of the work, particularly repetition of tasks perceived as dull.
Good book though if you want more information on ADHD/gifted versus just adhd kids and just gifted kids is Different Minds by Deirdre V. Lovecky.
