What do you mean poor performance ?

My synapse used to run on a 5€/mo VPS besides other stuff and ran fine and now runs on one of my on-premise servers (and not even my fastest, just some old ryzen 2700) with A BUNCH of other stuff besides it. Multiple users, a bunch of large federated rooms, bridges to other messengers … And it just runs fine with 0 issues.

Are you talking about running a synapse server for like a thousand people or on absolute potato hardware or what is the issue ?

There is one website, that I know of, that does not ignore DNT: geizhals. Also in germany you cannot ignore DNT by law (most still do).

The CalyxOS installer does that AFAIK, so it should be supported