It is not lag, it's more like your server simply doesn't know about the content yet because it didnt federate yet.

Say we make 2 servers, a.example and b.example and theres a community on a.example that is quire active.

now a user from b.example opens it, lettings its server know for the first time that the community even exists at all! b.example will not ask a.example for all the posrs on the community because, especially later, there'd simply be tol much, so your server only shows what it knows about.

I'm definitely not a "typical" case, just saying what I did:

A friend of mine used discord for his worldbuilding project and at some point when I asked him sth and he emailed me a bunch of images and texts (I don't use discord anymore) I was like "yeah no this is enough I'm setting up a mediawiki for you"

I spent about a week figuring shit out with NixOS containers, keycloak and some mediawiki thingies (gosh the openid connect plugin is cursed), and now he's happily writing away at his wiki (when he feels like it lol).

I'm not saying to do it like me, it's probably the most monumentally worst way to do it, but it works well enough.

Yes: Bitwarden.

Idk about the central instance, but I use my bitwarden (specifically vaultwarden) instance for my TOTP keys. I can just autofill and then it copies the current TOTP key and i can paste it in to log into whatever i'm logging into!