ticks-per

The default ticks-per settings are found in the bukkit.yml file and look like this:

ticks-per:
  animal-spawns: 400
  monster-spawns: 1
  water-spawns: 1
  water-ambient-spawns: 1
  water-underground-creature-spawns: 1
  axolotl-spawns: 1
  ambient-spawns: 1
  autosave: 6000

Recommended starting values

If you run a small server with just a few friends, thes values should work fine for a vanilla-like experience:

ticks-per:
  animal-spawns: 400
  monster-spawns: 1
  water-spawns: 30
  water-ambient-spawns: 30
  water-underground-creature-spawns: 30
  axolotl-spawns: 30
  ambient-spawns: 30
  autosave: 6000

If you start to notice any lag issues at all, these should be good for performance without sacrificing too much gameplay:

ticks-per:
  animal-spawns: 600
  monster-spawns: 4
  water-spawns: 50
  water-ambient-spawns: 50
  water-underground-creature-spawns: 50
  axolotl-spawns: 50
  ambient-spawns: 100
  autosave: 6000

For medium to large servers, these values should help keep your TPS at 20:

ticks-per:
  animal-spawns: 500
  monster-spawns: 10
  water-spawns: 125
  water-ambient-spawns: 100
  water-underground-creature-spawns: 100
  axolotl-spawns: 100
  ambient-spawns: 200
  autosave: 6000

Of course, this comes with the issue of far slower mob farm rates. Adapt it to your specific server needs.

What is the ticks-per setting?

One Minecraft tick is 1/20th of a second. So 20 ticks happens every second.

The ticks-per settings determine how often the server will attempt to spawn mobs of each type. For example, if axolotl-spawns is set to 40, the server will attempt to spawn axolotls every 40 ticks, or every 2 seconds.

• A lower ticks-per value means the server will try to spawn mobs more often (so faster spawns, more lag).
• A higher ticks-per value means the server will try to spawn mobs less often (so slower spawns, less lag).

The autosave setting

The default autosave of 6000 ticks (5 minutes) is usually fine for most servers.

You may want to increase it (make autosaves happen less frequently) if:

• You have a large world with many players, and autosaves are causing TPS drops.

You may want to decrease it (make autosaves happen more frequently) if:

• You have an unstable server that crashes often, and you want to minimize data loss.
• You have a small world with few players, and autosaves are not causing any performance issues.
• You have a fast drive, so autosaves are quick and do not impact performance much.

I would never recommend going above 10 minutes, and definitely not above 15 minutes, as that increases the risk of data loss significantly.
Even just a 15 minute loss of data can be very frustrating for players.

World-specific settings

YOu can change all of the settings for mob spawning per-world in the paper-world.yml config for each world, under the entities>spawning>ticks-per-spawn section. By default, everything is set to -1, which means it uses the global bukkit.yml settings.