To be clear, I'm not trying to make their argument for them since we spent probably 1 day working around it. I'm just passing along an anecdote. One day, Vary h

To be clear, I'm not trying to make their argument for them since we spent probably 1 day working around it. I'm just passing along an anecdote. One day, Vary header stopped working on one CDN and we had to fix it. When I spoke to our account rep (I literally had a weekly call with them due to our usage) he said they were phasing it out for performance reasons. Not long after we got notice from another CDN asking for similar consideration. I have no inside knowledge as to their infrastructure or systems that made this a requirement. I very much doubt it was the cost to hash, maybe more likely something to do with their network topology and how requests were routed from origin to regional tiers to PoPs? I'm totally speculating here. If this had been a necessity then I would have probably dug into the request more deeply. It was a "pick your battles" kind of thing. Extremely low cost on our side to change, no reason to bother if they claimed it would decrease problems on their side.