Comment by squirrellous

I don’t understand this argument. It seems to originate from capnp’s marketing. Capnp is great, but the fact that protobuf can’t do zero copy should be more an academic issue than practical. Applications that want to use a schema always needs their own native types that serialize and deserialize from binary formats. For protobuf you either bring your own or use the generated type. For capnp you have to bring your own. So a fair comparison of serialization cost would compare:

native > pb binary > native

vs

native > capnp binary > native

If you benchmark this, the two formats are very close. Exact perf depends on payload. Additionally, one could write their own protobuf serializer with protoc they really need to.