Like does content get mirrored to my instance and then mine distributes it ala BitTorrent or is my instance it’s own thing?
In effect, not really.
All the communities you’re subscribed to will now also have to push all their updates (posts, comments, upvotes) to your server, even when you’re not interacting with Lemmy.
As someone else mentioned, it would only be efficient once you have a decent (hard to pinpoint) amount of users on your server.
They’ll do it once, though. Then every time you view it, you’re helping the bigger servers by serving it from your instance.
Yes. Once for every post, comment and vote.
So say you have your own personal instance, and you use that to follow community news
on lemmy.world. If throughout the day that community receives 10 new topics, 50 comments and 100 upvotes, it would have to make 160 calls to your server.
So when you decide to read those 10 topics (if you even read all of them), you would then make roughly 10 api calls.
You would be saving those last mentioned 10 calls by using your own instance, but at the cost of 160 calls made throughout the day.
So you need just 15 more users on your instance to break even, if you have 17 in total, you’ve saved 10 calls.
The thing is that when you interact with the remote server directly it’s not 10 api calls, it’s 10 full-blown HTML webpages that have to be served to you, which are way bigger than REST API calls.