Federation takes almost no server load. It'd all the people loading images and comment threads that cause the server to slow down. Yes federation can break, especially due to unexpected code changes, but typically using a federated, lower user count site helps over all.
So what changed with Lemmy then? A few months back when I joined the ecosystem many instances including LW were unreachable for many hours a day. Joining up to a new instance didn't make LW content appear (as they were offline).
The issues today feel largely the same as a user, though less frequent. Am I misunderstanding?