To support decentralization and spread, should lemmy.world close registration at some point to prevent a performance overload due to too many users? Of course, if registration is disabled, there could be a hint placed somewhere near that from other instances you can interact with content on lemmy.world just like you had registered on it. There could be a link to join-lemmys instance overview.
It will. I have no lag on my accounts that aren’t on overran servers. And I mostly interact with content from overran servers.
My Lemmy.world and Lemmy.ml accounts can barely upvote without delays.