The problem basically boils down to a design feature (or flaw) in the original Lemmy code. The different instances update each other transaction by transaction. Each lemmy.world upvote, post, comment etc is sent to the other instances one by one. Because lemmy.world is in Finland and Aussie.zone is in Sydney, that takes about a quarter of a second.
Lemmy devs never pictured a situation where one instance would get so big that they couldn’t update everyone in a timely manner. Basically, lemmy.world generates more than four upvotes, comments, posts etc per second. So it took until this afternoon for me to see your comment.
The latest version of Lemmy code allows instances to open more than one stream of updates. When/if lemmy.world upgrades to that version, they’ll be able to open several channels to update the other instances.
