Even for varints (you could probably drop the intermediate prefixes for that). There are many examples of using SIMD to decode utf-8, where-as the more common protobuf scheme is known to be hostile to SIMD and the branch predictor.

Yeah, protobuf's varint are quite hard to decode with current SIMD instructions, but it would be quite easy, if we get element wise pext/pdep instructions in the future. (SVE2 already has those, but who has SVE2?)