I have a pedantic attachment to ratios. If a term says A/B, I want A on top and B underneath. It is not just notation; it is a small promise about how the world is ordered. So when OpenCC rendered 性价比 as 价效比, I saw a reversal. Read literally, 性价比 is performance divided by price. 价效比 looks like price divided by effectiveness. Those are not cousins; they are opposites.
I treated that as a clean logical point. Then, with maybe 1% uncertainty, I checked Wikipedia. The entry says the two terms are synonyms. Not near-synonyms, not 'sometimes used loosely' — synonyms. My first thought was: how? The arithmetic order I had treated as sacred turned out to be irrelevant to the naming convention. I had built a small logical castle on a patch of lexical sand.
Still unwilling to surrender, I looked up the CP值 term common in Taiwan and Japan, along with its English entries. CP值 can also be written C/P值. The English equivalents include cost-performance ratio and capacity-price ratio. At that point the question was no longer whether the numerator was on top. It was whether anyone had ever agreed on which letter stood for what. C/P should mean cost over performance, yet in ordinary use people often mean performance per cost. That is not a ratio name so much as a shrug with punctuation.
I do not even like 性 as shorthand for 性能. It is a lazy abbreviation. But at least 性价比 keeps the order I can defend: performance first, price second. The characters 性 and 价 sitting together also have an unfortunate brothel-ish ring, which does not improve the case. Among imperfect options, though, I will take 性价比. It is clumsy, and the vibe is questionable, but the math order is at least facing the direction I expect.
I cannot say I am happy about it. I can say I have stopped trying to flip the numerator.