Lemmy Server Performance
lemmy_server uses the Diesel ORM that automatically generates SQL statements. There are serious performance problems in June and July 2023 preventing Lemmy from scaling. Topics include caching, PostgreSQL extensions for troubleshooting, Client/Server Code/SQL Data/server operator apps/sever operator API (performance and storage monitoring), etc.
Specifically the database backend. Is the polling for notifications causing more database load? From my personal testing, lemmy.ml has the same performance problems with 0.17.4 that it does with 0.18.1 and I haven't seen anything in the code changes that are that significant with database.
My instance is missing both comments to this post. https://vlemmy.net/post/376384 versus https://lemmy.ml/post/1605318
Lucky yours did delivery inbound to lemmy.ml - it is the outbound queues of the servers with lots of active communities that is still failing badly in 0.18.0
At this point, on important topics like this, I go to the original server to make sure I'm not missing posts or comments, as Lemmy to Lemmy is really faltering.