We should not be optimising Mastodon so it can handle more people per server. We should be optimising Mastodon so it incentivises more serves with fewer people.
(And if you take that line of thinking to its logical conclusion, you arrive at the idea behind the Small Web: https://ar.al/2020/08/07/what-is-the-small-web/)
@aral I've only been here for two days, and came to that same conclusion. I joined a server with fewer users, and things are going well unless I try to interact with the largest server.