This. Clean code isn't about writing stuff like this. For what he's talking about the overhead of polymorphism is a major part of the total cost and his case is simple enough that there's little value.

However, the bigger your task gets the more value there is to polymorphism and in general the smaller the percent of total time goes to the polymorphism overhead.

And note that his attack is only on polymorphism, not the other aspects of clean code. I strongly suspect the compiler optimizes away much of the clean stuff I do but I have never checked. I also find profiling easier on cleaner code, it makes it very obvious where the time sink must be and thus what warrants expending effort to improve. Profiling almost always shows the vast majority of time going into the unavoidable (say, disk reads) and a small number of other routines. Spend your optimization effort on the spots that need it because 99+% of your code doesn't run often enough for it to matter.