Moira, see the link
See post 9. This hyper guy (my impression) is a past world memory champion. I could find quite a few similar examples.
Francis,
I would not argue that memorizing at high speed will give you a hyper feeling as if memorization was a drug but I do think the activity fits best those that have a propensity to be hyper. If you are under the impression that achieving new abilities in general can make you hyper, then maybe the kind of abilities you gain and that make you hyper may be related.
My impression of you being hyper ( maybe I should say creatively bubbly to distinguish it from the hyper type talked about in psychology manuals) came recently in your written comments when you suggested to me what you like the most about elections. Were you always frequently coming up with such creativeness, or do you find that this has become easier since you started excelling at speed cards?