How do I change world height, tick speed, or mob caps?

World height, tick speed, and mob caps are three different knobs that affect how your world grows, behaves, and performs. Each lives in a different place, so here's where to find each one.

The three settings

• Tick speed controls how fast crops grow, leaves decay, and fire spreads.
• Mob caps limit how many mobs can spawn (a big performance factor).
• World height is largely fixed by your Minecraft version.

How to change each

1. randomTickSpeed (crop/leaf growth, fire spread): In the Console run /gamerule randomTickSpeed 3 — 3 is the default. Lower it to reduce load, raise it for faster growth.
2. Mob caps: On Paper/Spigot, set spawn-limits in bukkit.yml / spigot.yml via the Files tab.
3. World height: This is fixed by version/datapack — 1.18+ raised the build limits. Custom heights require a datapack.

Tip: After editing server.properties or YAML config files, restart (or reload on Paper) for the changes to apply.

Frequently asked questions

Does raising randomTickSpeed lag my server? It can — higher values mean more block updates each tick. Raise it only temporarily if you need fast growth, then set it back to 3.

Can I lower mob caps to fix lag? Yes. Reducing spawn-limits in spigot.yml/bukkit.yml is a common and effective performance fix on Paper/Spigot.

Can I build higher than the vanilla limit? Only with a datapack that raises world height. The base limit is set by your Minecraft version.