Yes, that paper does make me angry :) I understand and agree with you that most code that exists today is inefficient and slow, but there is room for "let's after the lowest hanging fruit" in the discussion. Almost all projects these days are object-oriented in some form because complexity demands it. Performance and maintainability for modern software can be at odds along some axes and we pick the latter because our hardware gets better, and we might as well use it for that. That doesn't mean that there aren't places where you can see easy wins or that there isn't horribly inefficient software that ought to be optimized regardless but when you look at the broader picture "let's rewrite everything because it's in an inefficient language" is generally not actually an optimal strategy.