[Throwawayaerlei]

My understanding is that Pleroma was first and foremost designed to have a small memory footprint for small instances. As an Elixir program running on the BEAM (Erlang) runtime it ought to scale a lot better, but serious work had to be put into that. Not sure it's running on any sites as big as the big Mastodon ones.

[zimpenfish]

[1] has the biggest Pleroma at about 27k users - about 45th biggest according to the list on [2]

[1] https://the-federation.info/pleroma [2] https://instances.social