EntityLoom

EntityLoom is a performance plugin that targets the single biggest source of server lag: entities. It freezes the AI of mobs far from every player — pathfinding, targeting, and physics-heavy behaviour all stop — and restores it the instant someone comes near, so distant mobs cost you almost nothing. A per-chunk mob cap then trims overcrowded chunks, removing the farthest-from-player mobs first while always protecting named, tamed, leashed, ridden, and whitelisted entities like villagers and golems. Two lightweight, staggered tasks, an immutable config read off the hot path, and live /entityloom stats — profiled to be as light as the lag it removes.

More info at: https://aurovion.com