Beyond that, developers being conscientious of what they send over the wire, and being just a bit critical of what the framework or ORM produces also can yield substantial gains.
I say this as a “DevOps” guy who is responsible for budget at a mid-size startup, where we’re hitting scale where this becomes important. We save about 8 production cores per service that we convert from Rails to Go. Devs lose some convenience, yes, but they’re still happy with the language, and they’re far from writing hyper-optimized, close to the metal code.