Read the comment you’re replying to.

In it OP says it’s not slow, and the “hundreds of messages per second” you are referring to is not regarding the performance but the expected rate.

It’s possible for something to be fast, but only happen infrequently.

It just seems strange that the message rate is assumed to be in some very specific range where the performance of D-Bus is a problem (mentioned in the slides) yet the performance overhead of JSON is not a problem.