Mostly entities in the main world. We are fairly sure.
- Entities55%
- Chunk loading22%
- One plugin9%
- Everything else14%
- Lower the mob spawn limitsSafe
- Pre-generate the world borderTest first
- Move to a faster-CPU planHardware
If lag comes back after these, the server needs more CPU. Ask your host about faster single-core speed.
Made-up numbers, shown to illustrate the layout.