Your child is definitely gifted.

Lots of kids who are very careful in their approach to their work score lower on Processing Speed, is that his nature? Is he beyond careful and into 'anxious' territory? Is the physically coordinated in general?

Even though the Processing Speed is lower, it isn't lower enough to be worrisome, as long as there aren't issues that you can see in his life. With that very strong WM, he can probably compensate if the bottleneck is even real.
Love and More Love,
Grinity

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