Generally good but it makes it sound like what it calls the dynamic typing penalty is a matter of more instructions. If that was true Python would only be a factor of 2 slower or something like that. Instead the problem is that the cost of getting the value of an integer is first of all that after reading the type of the variable Python has to execute a fairly high entropy branch which will probably cost the branch delay penalty of 20 cycles or so. And then the extra memory lookup will cause a slowdown as well.