My son had a 50 point spread between all of his scores and the processing/speed score. He was tested when he was 6. Later, we found out that he is hearing impaired! We didn't know. Now he has a hearing aid and an FM system and is doing great.
We never retested so I have no idea if that got better. I think the brain is plastic and I believe/hope that his brain will rewire itself, if not normally, at least better.