Re 2, I would generally agree and there is a lot that can be done with caching. However, since writing services in Rust and Golang, there is whole other tier in speed. Architecture matters, code quality also matters, but Golang and Rust help a lot in making very fast services.

Yeah I don't disagree. To clarify. Rust, Golang etc - they give you a very noticeable advantage when it comes to writing good performant software with the assumption that you're putting in the effort on the design side. But poorly written Rust is likely going to be indistinguishable from poorly written Ruby.