hnz1979, how old is your ds? I think there's an ideal age range for IQ tests, and maybe your ds is very young for it?

That said, it was one day, and you say he wasn't engaged. That right there would tell me as a parent to perhaps take the results with some caution.

As for processing speed, my DYS has a low average processing speed attributed to perfectionism. If you and your dh are gifted, chances are your ds is too. He may or may not have other issues going on that affected his test on that day.