spawn-limits

Spawn limits can be configured in the bukkit.yml file. By default, it looks like this:

spawn-limits:
  monsters: 70
  animals: 10
  water-animals: 5
  water-ambient: 20
  water-underground-creature: 5
  axolotls: 5
  ambient: 15

Recommended starting values

If you run a small server with just a few friends, these values should work fine and still give a fairly vanilla experience (these are similar to the default Bukkit values):

spawn-limits:
  monsters: 60
  animals: 12
  water-animals: 5
  water-ambient: 12
  water-underground-creature: 4
  axolotls: 4
  ambient: 4

For medium-sized servers (10-30 players), you can try these values:

spawn-limits:
  monsters: 35
  animals: 7
  water-animals: 3
  water-ambient: 5
  water-underground-creature: 2
  axolotls: 2
  ambient: 2

And for larger servers, try these values:

spawn-limits:
  monsters: 20
  animals: 4
  water-animals: 2
  water-ambient: 2
  water-underground-creature: 1
  axolotls: 1
  ambient: 1

Mob spawn range

Because lowering the spawn rate causes fewer mobs to spawn, you may want to make the mobs that do spawn closer to the players.

Please see the mob-spawn-range page for help on doing this. As a general rule: if you lower the spawn limits, you should lower the mob spawn range as well.

A note on `per-player-mob-spawns`

This page relies on the per-player-mob-spawns option being set to true in your paper-world-defaults.yml file. This is highly recommended, and the guide does not support this option being set to false.

Please see this page for more info on what this option does and why you should enable it.

What are spawn limits?

Spawn limits are probably the most important configuration option for optimisation, perhaps with the exception of simulation-distance.

Spawn limits are sometimes also referred to as “mob caps”. For the sake of this guide, they’re effectively the same thing.

It effectively controls how many mobs (animals, monsters, etc) can be present in the world at any given time.

With per-player-mob-spawns enabled, this limit is calculated per player in the world, meaning that each player gets their own “quota” of mobs.

When the number of mobs around a player goes above this limit, no new mobs will be able to spawn until the number of mobs drops back below the limit.

Basically, a monster mob cap of 70 means that up to 70 monster mobs can be present around each player at any given time, for example.

The different mob types

Thanks to https://paper-chan.moe/paper-optimization/#mob-categories, we have a detailed list of what mobs fall into each category.

Feel free to search for specific mobs using your browser’s search function (ctrl+f) if you’re not sure which category they fall into!

Monsters

Warden
Evoker
Wither
Hoglin
Cave Spider
Camel
Husk
Zoglin
Slime
Bogged
Zombified Piglin
Pillager
Wither Skeleton
Zombie
Nautilus
Stray
Blaze
Witch
Piglin Brute
Spider
Drowned
Phantom
Illusioner
Ravager
Vindicator
Creeper
Parched
Elder Guardian
Giant
Breeze
Zombie Horse
Zombie Villager
Endermite
Silverfish
Shulker
Ghast
Vex
Piglin
Guardian
Enderman
Magma Cube
Ender Dragon
Skeleton
Creaking

Animals / creatures

Wolf
Bee
Horse
Chicken
Frog
Allay
Pig
Skeleton Horse
Llama
Polar Bear
Mule
Armadillo
Donkey
Parrot
Rabbit
Fox
Happy Ghast
Goat
Mooshroom
Cow
Strider
Cat
Sniffer
Ocelot
Trader Llama
Tadpole
Wandering Trader
Panda
Turtle
Camel
Sheep

Ambient

Yep, that’s it… you can probably lower this one quite a bit, if not completely to 0. I’ve seen some servers’ spark reports showing thousands of bats where optimisation has gone horribly wrong…

Water animals / water creature

Nautilus
Dolphin
Squid

Water ambient

Cod
Pufferfish
Salmon
Tropical fish

Water underground creature

Glow squid

Axolotl

Pretty obviously… axolotls. They’re so cute they get their own category.

Misc

Everthing else:

Bamboo Raft with Chest
Cherry Boat with Chest
Eye of Ender
Marker
Jungle Boat with Chest
Interaction
Spectral Arrow
Wind Charge
Item Display
Mangrove Boat with Chest
Minecart with Chest
Snowball
Item Frame
Mannequin
Firework Rocket
Evoker Fangs
Area Effect Cloud
Minecart with Command Block
Dark Oak Boat
Oak Boat
Lingering Potion
Shulker Bullet
Acacia Boat with Chest
Spruce Boat
Acacia Boat
Birch Boat with Chest
Glow Item Frame
Spruce Boat with Chest
Bamboo Raft
Jungle Boat
Player
Thrown Bottle o’ Enchanting
Leash Knot
Cherry Boat
Primed TNT
Wither Skull
Villager
Text Display
Minecart with Furnace
Item
Ominous Item Spawner
Trident
Mangrove Boat
Thrown Ender Pearl
Snow Golem
Arrow
Pale Oak Boat with Chest
Experience Orb
Splash Potion
Minecart
Painting
Block Display
Copper Golem
Iron Golem
Falling Block
Armor Stand
Pale Oak Boat
Dragon Fireball
Minecart with TNT
Dark Oak Boat with Chest
Oak Boat with Chest
Llama Spit
Thrown Egg
Small Fireball
Fishing Bobber
End Crystal
Birch Boat
Fireball
Minecart with Monster Spawner
Lightning Bolt
Minecart with Hopper