Hacker News Reader

Yes? It’s written in RoR.

Is the ActivityPub spec just as bad, or would it be performant if written in a proper language?

There are other clients, like gotosocial written in Go, so a comparison is possible, but not sure if someone has already done that.

Pleroma is an Mastodon clone written in Elixir https://git.pleroma.social/pleroma/pleroma