Well, my opinion is not entirely uninformed or off the cuff. I was briefly Director of Community Life for The TAG Project. I homeschooled my gifted-learning disabled sons. I attended a gifted conference and was a low-level presenter. I did plenty of reading on the subject for a time and participated in lots of discussions with other informed individuals in the gifted community, including some fairly important professionals in this niche field.

First of all, most IQ tests do not go above 140. So anything anywhere near 140 may only be telling you the person is at about the limits of what the test can measure. Even for those tests that do go above 140, it requires a qualified assessor to interpret it properly. The smartest kids often do not measure as being all that smart by standard measures. "Genius" is, basically by definition, someone who thinks differently from others. So measuring the kid who is radically different by standard measures has a track record of missing a lot.

In recent years, there is increasingly research into and available literature on the idea that gifted kids have different minds. They are not merely "more" of something, they are fundamentally different. The correlation of "speed = intelligence" is a rubric which assumes gifted kids are simply "more" of something. Yes, they do tend to be faster than average, even if they are slow compared to other gifted students, but it's really a lot more complicated than that and I think the emphasis on speed does a huge disservice to the gifted community.

The "fast = smart" paradigm is a really major metaphor for giftedness in the world. For example, Stephanie Tolan's essay "Is it a cheetah?" is very popular: http://www.stephanietolan.com/is_it_a_cheetah.htm I once wrote something of a polite rebuttal to that which used redwoods and gazelles as other metaphors. I am not terribly important in the world and it did not become popular (and is no longer online, unless it got captured on The Way Back Machine). I think the cheetah metaphor does a disservice to the gifted community in part because of the unstated assumption that smart people are all dangerous predators. Gazelles are just as fast and are not predators. Why not use that as a metaphor?

Anyway, I am quite busy today so I don't plan to argue this or dig up detailed supporting links. If you really want to look into it, HN's member who goes by the handle tokenadult is a good resource on the topics of intelligence and education. I believe his profile contains links to resources and his posting history, both comments and articles, is likely to be enlightening. (Though I have no idea if he would agree with any of my views above. He and I are not close. We haven't talked in quite a long time. But I have reason to believe he remains far more current on these subjects than I am.)