nautilus, interacting with creepvine, and ice and fire, will cause a pretty big lag spike with occasional crash with this crash log:
crash-2020-01-14_00.49.45-server.txt

-tested with fossil and archeology, ice and fire, better diving: lag spike with occasional crash
-tested without fossil and archeology, with ice and fire and better diving: no lagspike nor crash
-tested without nautilus natural spawning: no lagspike nor crash, if set them to spawn after the world is loaded they will not cause any lag or crash for some reason (?)
-tested without better diving with nautilus natural spawning and ice and fire: no lagspike or crash
-tested without ice and fire with nautilus natural spawning and better diving: no lagspike or crash

issue is with

better diving. tell their devs

java.lang.NullPointerException
at meldexun.better_diving.block.AbstractBlockCreepvine.setCreepvine(AbstractBlockCreepvine.java:32)