Is the rate limit fine tuned to initial history sync from new federated communities (ie if you join a new community only 10-20 days of posts history will sync after which point only new posts will received and no further history will be synced).

Or is the rate limit more like the instance overall can perform a set number of federation actions in a given period, and the volume of new federated content from larger instances prevents new history from being synced.

I noticed when subscribing to new communities new posts, comments, upvotes sync pretty much instantly history seams to be the part the gets bogged down.

[–] [email protected] 2 points 1 year ago

The second option is the more accurate description of what's going on, 0.18.3 should alleviate that somewhat as inactive instances will start being phased out now. Previously even dead instances took up time during the update cycle having all activity pushed to them even if they were dead.