While playing in single player, I noticed I was getting block lag. I've never experienced this in SP, just when playing on a server. The log contained this:

[09:09:19] [Server thread/WARN] [FML]: Recurrent Complex loaded a new chunk [33, -41] in dimension 0 (overworld) while populating chunk [34, -41], causing cascading worldgen lag.

This message repeats between 12-20 times listing sequential chunk numbers.

Still causing issues in 1.47.

[22:05:47] [Server thread/WARN] [FML]: Recurrent Complex loaded a new chunk [224, 2] in dimension 0 (overworld) while populating chunk [223, 2], causing cascading worldgen lag.
[22:05:47] [Server thread/WARN] [FML]: Please report this to the mod's issue tracker. This log can be disabled in the Forge config.

Duplicate of #155. I recommend pushing down the structureSpawnChance and / or tree decoration replacement chance down in the config for now. A fix will, hopefully, soon follow.

I got the same thing on my multiplayer server
crash-2018-09-22_17.28.51-server.txt
:

I encounter the same issue causing my server stopped...

crash-2018-09-25_13.02.36-server.txt

Its like playing minesweeper! Never know when you are going to get lucky! https://hastebin.com/izisejidil.md Turns out luck isnt usually on my side.