What I mean is, why not just a bi-directional mirror, with several servers in the larger users goes? Can the federation API be leveraged to just do that to address the dramatic load increase? Folks firing up Lemmy servers all over that only have a tiny portion of unique content are likely to provide poor experiences and stress the federation subsystem on the larger lemmy.world and lemmy.ml sites.
Are you wondering if one instance can be spread across multiple machines? I don’t think that’s possible and seems unnecessary. I say that because spreading users onto more instances creates less load on the larger instances, not more. Edit: I guess you can scale instances across machines!