Title kinda explains it all. Somehow the game goes to literal seconds per frame upon rendering a mob with invalid UUID with "mobowner" enabled. Normal nametags work fine. Future nametags work fine.
Disabling the mobowner thing instantly fixes it.
Server: 2b2t. Coords: available upon request for debug and not for murdering doggo. Discord: Robijntj3#1294
Screenshot of doggo:
