To add something to the topic, reaction time can be divided into two components. A processing component and a physical component: http://lesacreduprintemps19.files.wordpress.com/2011/04/jensen-2011-the-theory-of-intelligence-and-its-measurement.pdf
Black people may not dominate in the higher IQ range, but they probably do in the physical component of reaction speed.
Also, I had a mistaken impression about the correlation between reaction time and g. Apparently its no better than 0.2-0.4, much worse than the cited 0.6 that probably caused the buzz. Still, it makes sense for higher IQ to have an effect on the processing component; decision making time is reduced in the highly intelligent. Fighting games were brought up, and I have often wondered if there is some intrinsic quality that makes the top tiers full of east asians and black people. This goes some way towards explaining that. Probably not true for Smash because that is a gay kiddy game and would be likely to attract damaged autistic My Little Pony types more than anyone else.