I do need to comment that it is not true that most GT individuals, let alone all of the "truly gifted", score below average in processing speed. The large-scale data sets say that GT individuals score, as a group, higher in processing speed than NT individuals do. That being said, processing speed does tend to be -relatively- lower than higher-level cognitive areas (reasoning/abstraction), but still usually in the Average to High Average ranges (and sometimes much higher). And, of course, some GT individuals do score very low in processing speed, for a variety of reasons. IOW, the whole range of processing speed performance occurs somewhere in the GT population.
And as much as I think that we overpathologize in our culture, I would also hesitate to throw out all of the data (including fMRI and genetics studies) on ADHD.
Along both of those lines, I would also be conservative about looking for an ADHD diagnosis right now. If something is interfering with your DC's happiness, growth and development as a whole person, or access to resources that she needs, then it may be worth investigating further, which may include a comprehensive psychoeducational or neuropsychological evaluation. But I wouldn't go in fishing for a specific diagnosis.
