Nothing kills the exploration experience faster than chunk generation lag. When a player walks into unloaded territory, the server has to generate terrain, caves, structures, and biomes on the fly - consuming massive CPU resources and causing TPS drops that affect everyone online.
What Is Chunk Pre-Generation?
Minecraft worlds generate lazily - chunks only exist once someone (or something) loads them. Pre-generation forces the server to create chunks in advance, saving the terrain data to disk so future loads are instant reads instead of expensive calculations.
For modded servers, this is even more critical. Modded terrain generation (biomes, structures, ores from tech mods) is significantly more expensive than vanilla.
Installing Chunky
Paper/Spigot/Purpur
- Download Chunky from Modrinth or SpigotMC
- Drop the JAR in your
plugins/folder - Restart the server
Fabric
- Download the Fabric version from Modrinth
- Place in
mods/folder - Restart
Running Pre-Generation
Basic command:
/chunky radius 5000
/chunky start
This generates a 5000-block radius circle around spawn (0,0) - covering a 10,000x10,000 block area.
Recommended Radii
| Server Type | Radius | Disk Space | Time (7950X3D) | |------------|--------|------------|-----------------| | Small Survival | 3,000 | ~2GB | 10-15 min | | Standard Survival | 5,000 | ~5GB | 25-40 min | | Large Survival | 10,000 | ~15GB | 2-3 hours | | Network Lobby | 500 | ~100MB | 1-2 min |
Advanced Options
Generate specific shapes:
/chunky shape square
/chunky radius 5000
/chunky start
Generate the Nether and End:
/chunky world world_nether
/chunky radius 2000
/chunky start
Pause and resume:
/chunky pause
/chunky continue
Performance During Pre-Generation
Pre-generation is CPU-intensive. On a Space-Node Ryzen 9 7950X3D server, Chunky generates roughly 500-800 chunks per second for vanilla and 200-400 for modded.
Tips for running pre-gen:
- Run during off-peak hours or before your server opens
- Pre-gen doesn't need to complete in one session -
/chunky continuepicks up where you left off - Monitor TPS with
/tps- if it drops below 18 during pre-gen with players online,/chunky pause
When to Pre-Generate
- Before server launch: Always. Pre-gen at least a 3,000-block radius before opening to players.
- After version updates: New Minecraft versions often change terrain generation. New chunks will be different from pre-generated ones, creating chunk borders. Consider pre-generating a fresh world.
- Before events: If you're hosting an exploration event, pre-gen the target area.
- After adding terrain mods: Mods that change world generation will only affect newly generated chunks. Pre-gen ensures consistency.
World Border
Pair pre-generation with a world border to prevent players from going beyond pre-generated terrain:
/worldborder set 10000
/worldborder center 0 0
This sets a 10,000-block diameter (5,000 radius) border centered on spawn - matching a 5,000-radius pre-generation.
Storage Considerations
Pre-generated worlds use more disk space since chunks that might never be visited are already saved. Make sure your hosting plan has enough storage. Space-Node plans start at 50GB NVMe SSD, with higher plans offering up to 200GB - more than enough for even aggressively pre-generated worlds.
Pre-generation is a one-time investment that pays off in smoother gameplay for the entire life of your server. Spend the 30 minutes setting it up before launch, and your players will never experience that frustrating chunk generation stutter.
