In theory, they can. But it depends on how it’s deployed.

From my cursory look at the deployment docs, Lemmy’s default deployment option is via docker. It relies on a postgreSQL server, which may or may not scale horizontally depending on the admin’s choice of implementation. For example, a deployment on AWS using Aurora would theoretically utilize auto-scaling.

I haven’t personally deployed an instance so, grain of salt.

EDIT: A good discussion about DB scaling here: https://github.com/LemmyNet/lemmy/issues/3005

AFAICT no. There is an open issue on the Lemmy GitHub repo. In general, all ActivityPub services I’ve used have this same account stratification problem.

It seems like a common issue among ActivityPub services that people flock to the most popular instance and this causes problems. Why can’t load balancing happen transparently? It seems like the main thing that actually makes a difference between which instance users want to join is what the moderation will be like. Like I don’t want to be forced to sign up for an instance with a high amount of censorship compared to the rest of instances.

So maybe user registration should start from a centralized site that can describe the trade-offs of joining the various instances, and users don’t get to select their specific instance by default, but rather they select based on a loose moderation policy, and then load-balancing occurs on the backend.

EDIT: I also want to be able to migrate between instances without losing my community subscriptions.