Minecraft version: 1.12.2
Forge version: 1.12.2-14.23.5.2768
mods: OTG and Biome bundle
java version: "1.8.0_201"

I can find anything unusual in the logs, if needed I can still add them.
My server is struggling even when there are no players on and visualVM gives me this, googling gives me abandoned github threads, hurray.

Problem might not be caused by OTG, I'll try my lock on the forge forums instead.

Hey, thanks for reporting. Will assume this is fixed, feel free to re-open if not.