Pregenerating your world will enhance performance by a lot. If all the blocks are already placed, your server can handle much more traffic, than when they have to be generated live.

Thinking about other plugins to pregenerate? Stop. They are not compatible.

Create a world without any players on it (see Getting Started for how you do that)

Pick a size

For selecting the right size, we recommend a number between 2.5k and 12.5k. 2.5k is more than enough for 10 players per day, and 12.5k is more than enough for over a hundred players per day.

This is the value you will use as <radius> in the next step.


  • Higher sizes cause increasingly longer generation times.

  • Be prepared to wait hours up to days for your generation to be finished.

  • The time depends on the size of the pregen and the hardware of the server.

  • You can always expand an existing generation -> start small.

Pick a center

  • Generally you don't need to specify a center

  • if you want to set the center at your location, use center=self

  • if you want to set the center by a coordinate, use center=0,0

Run the pregen:

  • If you are in the world: /iris pregen start <radius>

  • If you are in the server: /iris pregen start <radius> world=<worldName>

  • If you are in the console: iris pregen start <radius> world=<worldName>

The <worldName> is the name of the world.

The <radius> to select is based on preference and use-case.

Entering a radius of 1000 gives you a 2000 by 2000 world, which means you can travel 1000 blocks in any direction from the center of the world (0, 0). Here is a diagram:


If you need to restart your server during a pregeneration, it is safe to do so at any time. You can ignore any errors about threads not shutting down.

After starting your server again, resume the pregen with the same command you entered before. Iris will skip any chunks that were already generated.

Removing Iris after pregenerating can cause numerous issues. See the FAQ entry about this.

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