On the Fireside Fedi interview with Jerry ( the admin of Infosec.Exchange Mastodon instance ) a scary truth was suddenly revealed ( on 34:11 ): Just to keep the instance up and running he needs to spend up to $5000 a month, pretty much out of his pocket. Donations to the instance barely cover any of that. And if he will ask people to pay to use it, they will, rightfully so, switch to a different instance.
Seems like an optimization that is not really needed. The data format is not really the bottleneck, there are ActivityPub relays that can send messages in bulk and ActivityPub is built on LinkedData, which means that there plenty of powerful libraries in most languages that can parse and produce JSON in a way that keeps application developers with a consistent semantics. The more people try to change the data format in the sake of “efficiency”, the less portable and useful it would be.
Yes and no. Most of the current software do authentication by using HTTP Message Signatures, so after you fetch the actor’s public key every request is authenticated by seeing an HTTP header, which makes it no different most common authentication schemes.