It's like the problem is the ambiguous definition of "premature". I think by itself the phrase is taken to mean to keep the code high level and abstract as lon

It's like the problem is the ambiguous definition of "premature". I think by itself the phrase is taken to mean to keep the code high level and abstract as long as it might still need to change, and then only optimize once it's overall structure is established, because once you start optimizing for performance you are carving stone and destroying flexibility. But the full context shows that the word "premature" in this context means to say that it's premature to optimize before you even know what to optimize.