Pre-generate your world with Chunky to stop exploration lag

Three players head off exploring with elytra, and the whole server crawls. Nothing unusual: every unknown chunk has to be generated (terrain, caves, structures, light) during the tick. Pre-generating means doing that work once, in advance, when nobody is playing.

Install Chunky

Chunky exists for Paper, Fabric, Forge and NeoForge. Drop it into plugins/ or mods/ and restart.

Start the pre-generation

/chunky world world
/chunky center 0 0
/chunky radius 5000
/chunky start

A radius of 5,000 blocks makes a 10,000 × 10,000 square, about 390,000 chunks. Allow several hours depending on the CPU: run it at night, or with the server closed. /chunky pause and /chunky continue stop and resume without losing anything.

Do the same for the Nether (world_nether, a radius eight times smaller is enough) and the End if you keep it open.

Set the border

Without a border, players end up leaving the prepared area. With the ChunkyBorder plugin or the game command:

/worldborder center 0 0
/worldborder set 9800

Keep the border slightly inside the generated area (here 9,800 for 10,000): chunks at the edge are loaded when a player gets close.

How much disk space?

Roughly allow 2 to 4 GB per 100 million square blocks of surface, more with recent versions (deep caves) and generation mods. Check free space before starting a large radius.

Which radius?

Active players	Suggested radius
under 30	3,000 to 5,000
30 to 100	5,000 to 8,000
over 100	8,000 and more, or a border that grows each season

Widening the border each season, after a new pre-generation, makes people want to explore again, and makes a good opening event.

Pre-generation is one of the settings the anti-lag configuration reminds you of: it often weighs more than all the others put together.