It's marketing bullshit. He probably wrote a statement in C++ and measured the time it takes to execute, I have no idea (also impossible to know what sort of statement). numbers suggest around 2% accuracy (7.1), that's pretty impressive given that we measure "code responsible for rendering a typical web page" per "function" over "effective C++ statement". All of those well defined in his textbook I bet.
It's more likely he just rounded a number of results and rounded to the first decimal place to display it better, not to suggest some level of accuracy.
