Indirection kills performance nowadays. I did a bunch of benchmarking a couple years back and found that you can parse MessagePack and CBOR faster than Protobuf if you know the types and serialize directly into them. Even if field order isn't known and you use non-allocated field strings.

Well in a language that allows you to generate compile time specialized serde code like Nim or Zig. Maybe C++ has enough compile time reflection to do it now as well?

I don't know enough about Rust's serde, but it seems like there'd be a lot of performance overhead with it's design and the limits of Rust's macro and compiler system.