You have outdated structure files in your mod. This causes minecraft to try to update them every time they are loaded, leading to extra memory and cpu usage during worldgen. Please update your structures to match the mc version you are releasing for.
This should be as easy as loading them into game and re-saving them or using a mod to load them into a StructureTemplate and writing them back out to nbt.
1.7.5 - 1.20.1
You have outdated structure files in your mod. This causes minecraft to try to update them every time they are loaded, leading to extra memory and cpu usage during worldgen. Please update your structures to match the mc version you are releasing for.
This should be as easy as loading them into game and re-saving them or using a mod to load them into a StructureTemplate and writing them back out to nbt.