I'm not certain what is happening here. I'm looking into figuring out why connecting to a server takes such a long time. As such I've profiled joining and discovered this:

Join Snapshot for Enigmatica 5

It seems like JER is doing some loot table call that is causing structurize to reload all of its structures for 30 seconds.
Not certain what a solution could be.

JustEnoughResources-1.15.2-0.10.1.77

Closing old version issues

Hmmm, related lines of code https://github.com/way2muchnoise/JustEnoughResources/blob/master/src/main/java/jeresources/util/LootTableHelper.java#L155

I do rebuild the loot tables there, no clue how much tables they add. However 30s seems like a long time.