[detaro]

Does, not can. If you look at lists, there are tons of tiny instances: experiments, some people using their own instance as their private homepage, or just one for a few friends. People being able to do that is a strength of a federated system, and it's far from clear it actually is "wasting" something without looking into it in a lot of detail. It's not like all of these instances sync completely with each other.

The biggest instance has 250k users, and the top 10 instances together have 600k user (75% of of those 800k). I don't have info how these large instances map to actual servers, but I don't think Mastodon currently has a lot in the way of features to split an instance across machines.

(Data from https://instances.social)

[hugogameiro]

You can split Mastodon to several servers easily. Postgres, Redis, Sidekiq, Streaming API, Puma, Nginx and Media Storage can all be placed on different servers. Even multiples for each. You can read here about https://medium.com/@Gargron/scaling-mastodon-1becde463090 how Eugen had Mastodon.social running a few months ago.