To my understanding comments are ignored by compliers and runtimes having them makes no difference when the code is actually running. I may be wrong on this point though.
I was referring to this line
If it’s not immediately obvious what your code does by reading it, you should rewrite it so it is
Code that is written for human readability omits an amount of optimisations languages have in compilers, jits, and runtimes. As code is read by machines several orders of magnitude more then a human, why make the code 20 to 30% slower for a computer to read just so an engineer can read it 40% faster?
With that being said, not all code needs to be optimised that hard. There are times where you don't need that 20 to 30% increase in application runtime and writing code that is readable or "self documenting" works well enough.