[honkhonkpants]

Is X faster than Y will be tough to determine without a really detailed treatment of the use case. For example in C++ you want to account for the unavoidable construction of your class type, its inevitable destruction, how long it takes to put it on or take it off the wire, how often you might expect to miss the cache when referencing it, whether the type of movable or copyable and how expensive that is, whether or not you can reset it for reuse without destroying it, and much more. If you were to compare to protobufs I doubt that you'd find serialization and deserialization to be the predominant costs. I don't know what the cost breakdown looks like for capnproto, but maybe kentonv has standing benchmarks.