Uh, is that supposed to be ironic?
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And I disagree with that person.
And yes, efficiency isn't subjective, but you are still free to (personally, "subjectively") choose differents metrics to define it (objectively).
What you are speaking about is not "efficiency" as a concept but a special form of "efficiency", kind of like the difference between the concept of "a house" in general and a specific house that has been built somewhere.