Chunky Minecraft: pre-generate your map and reduce lag

Pre-generating chunks is one of the best ways to improve the smoothness of a Minecraft server. With Chunky (available on our site as a Modrinth mod or a CurseForge plugin), we tell the server to generate map areas in advance instead of waiting for players to discover them live. The result is fewer generation spikes, less stutter during exploration, and a cleaner base for map renders.

At BoxToPlay, we recommend doing this before opening a world to players, especially if you want exploration to stay smooth from the start.

Why Chunky is so useful

When a player moves into unexplored terrain, the server has to generate chunks on the fly. That process uses CPU, memory, and disk access. On a small map, you may barely notice it, but on an active world, with multiple players or several dimensions, the impact becomes much more visible.

With Chunky, you can:

• pre-generate a specific area of your world
• run generation for the Overworld, Nether, or End
• monitor progress with processed chunks, percentage, ETA, and generation rate
• pause and continue later
• use different selection shapes depending on your project

Chunky is designed to generate chunks efficiently, and it relies on the server for the actual world generation. That means it usually works well with custom generation too.

Before you start

A few best practices make a real difference before launching a pre-generation task:

• do it before players join whenever possible
• start with a reasonable radius, such as 5000 blocks, then expand later if needed
• remember that larger worlds can use a lot of disk space
• if you use a map rendering plugin, it is often better to disable rendering temporarily during generation
• confirm that Chunky is installed correctly by simply running /chunky

The simplest command to pre-generate a map

In the most common case, you want to generate an area around the center of the world. Chunky lets you do that with two very simple commands:

/chunky radius 5000
/chunky start

By default, Chunky typically works with a square selection in the Overworld centered at 0 0. If you have not changed anything, this starts generation around the center of the map.

If you prefer to define everything directly in one start command, you can also specify the world, shape, center, and radius explicitly.

/chunky start world square 0 0 5000

This is useful when you want to be very clear about the active selection.

Pre-generating the Nether and the End

Chunky is not limited to the Overworld. You can target other dimensions as well. The exact world name depends on your setup, but common names are usually:

• world or overworld for the Overworld
• world_nether or the_nether for the Nether
• world_the_end or the_end for the End

Example for the Nether:

/chunky world world_nether
/chunky radius 5000
/chunky start

If you are unsure, display the current selection first with:

/chunky selection

Choosing the right generation shape

Radius is not the only useful setting. Chunky also lets you choose a shape for the area you want to generate. The most practical options are usually:

• square, for a simple, easy-to-manage area
• circle, for a more natural radius around a center point
• selections based on corners, if you want to frame an exact region

Example with a circular generation around spawn:

/chunky shape circle
/chunky spawn
/chunky radius 3000
/chunky start

Example with a selection defined by two corners:

/chunky corners -500 -500 500 500
/chunky start

This is very handy when you already know the exact limits you want.

Using the native world border

If you have restricted your world limits using Minecraft’s native world border (configured via the /worldborder command), Chunky can automatically import its center and radius. This is one of the best ways to avoid generating too much terrain without having to re-enter coordinates.

/chunky worldborder
/chunky start

This matters because even a slightly larger radius can dramatically increase final world size. It is better to stay aligned with the playable area.

Tracking progress clearly

When the task starts, Chunky normally prints useful information in the console:

• number of processed chunks
• completion percentage
• estimated time remaining
• chunks per second
• current chunk location

If you do not see these updates in game, you can request them manually:

/chunky progress

You can also reduce message frequency:

/chunky quiet 5

Here, Chunky will wait 5 seconds between progress messages.

Pause, continue, and cancel

On a Minecraft server hosting environment, pre-generation can take a long time. The good news is that you do not have to finish everything in one run.

To pause and save progress:

/chunky pause

To continue later:

/chunky continue

To fully cancel a running or saved task:

/chunky cancel

Keep in mind that canceling does not delete chunks that were already generated. It only stops the task itself.

Which pattern should you use?

Chunky also lets you define the generation order with patterns. This does not change how many chunks are generated, only the order in which the work is done.

The main patterns are:

• region, the default and recommended mode
• concentric, from the center outward
• loop, from one side to the other
• spiral, in a square spiral

In most cases, region remains the best choice. It is the recommended default because it is efficient for traversing the selected area.

/chunky pattern region

If you have a very specific use case, you can test another pattern, but for standard use there is usually no need to change it.

Practical tips to reduce lag during pre-generation

Chunky is already designed to run as fast as possible, but final performance still depends on your server. To get better results:

• use a fast CPU, because chunk generation is very sensitive to processor performance
• make sure you have enough threads available
• run the server and world on a fast SSD
• allocate enough RAM, often at least 4 GB depending on the project
• on Paper, chunk generation behavior can benefit from the platform’s performance improvements
• if map rendering is active, generate first and render afterward

BoxToPlay Hosting Recommendation:
Pre-generating with Chunky is tolerated on our game servers, even though it consumes a massive amount of CPU and disk resources. This works fine for standard map sizes (typically with a radius up to 5,000 or 10,000 blocks maximum using /chunky radius 5000 and /chunky start), as long as you are not trying to generate a huge 400 GB world that runs for an entire day.
If you plan to have a gigantic map, we highly recommend running the generation locally on your own computer first. You can then zip your world folder, upload it via FTP using a client like FileZilla, and use the unzip button in the FTP file manager on your BoxToPlay panel to extract it.

Common mistakes to avoid

Starting with a huge area immediately

This is the classic mistake. A slightly bigger radius can mean far more chunks than expected. Start smaller, check the required time and world size, then increase gradually.

Rendering the map at the same time

If a map renderer is working in parallel, generation can be slower and the final render may be less clean. It is better to separate the two steps.

Forgetting that some add-ons can cause issues

Plugins, mods, or data packs can sometimes cause slowdowns, deadlocks, or crashes during generation. If something goes wrong, try a lighter setup first to isolate the cause.

Assuming Chunky replaces server world generation

Chunky does not generate terrain by itself. It asks the server to do it. If custom world generation has a problem, the issue often comes from the world setup or the related add-on.

Misaligning your world border

If the world border or other server limits are smaller than the generated area, you can run into strange behavior, including spawn-related issues outside the intended zone. It is better to verify those settings before launching a long task.

Can you pre-generate an existing world?

Yes, and that is a very common use case. Chunky skips chunks that already exist and only generates missing ones. This makes it very practical for expanding an active map without rebuilding everything.

What if you generated too much?

Chunky also includes the /chunky trim command to delete chunks outside your selection. It is powerful, but it must be used carefully, because deleting chunks cannot be undone without a backup.

Before using that kind of action, always make a full backup of the world.

Our recommended workflow at BoxToPlay

If you want a simple and reliable method, this is the workflow we often recommend:

1. install Chunky and verify that /chunky responds
2. define the target world
3. choose a simple shape, usually square or circle
4. start with a moderate radius
5. monitor progress and ETA
6. pause if needed
7. render the map again after generation if you use a map tool

For many projects, this preparation alone is enough to make exploration much smoother for players.

If you want to set up Chunky in the right conditions on reliable and high-performance Minecraft server hosting, we at BoxToPlay offer a simple way to test your project at no cost: Start your free trial.