Three Dash Structure Optimizer

Three Dash Structure Optimizer

Faster structure generation and smoother server ticks for Minecraft 26.2 and 26.3 - without changing what your world contains.

A server-side performance mod for packs with many structure mods. It works on its own - no other optimization mods are required. It also works alongside C2ME, Lithium, FerriteCore, zFastNoise, zFastSurface and Structure Layout Optimizer, so you can use any of them or none. The benchmark below was run on packs that already use those mods, because that is what most packs run.

Benchmark results

Setups compared: 1 = Fabric + Chunky + a 58-jar pack of structure mods; 2 = setup 1 + zFastNoise, zFastSurface, C2ME, Lithium, FerriteCore, Structure Layout Optimizer; 🟢 3 = setup 2 + Three Dash Structure Optimizer 2.0.0 (warm template cache). Ryzen 5 5500, server on 10 threads, Minecraft 26.2 on Fabric, mean of 3 measured runs per setup.

Table 1 - chunk generation speed (Chunky)

Time to generate a circle of 3,481 chunks at normal structure density, and of 729 chunks with a 72x structure datapack (same seed, fresh world every run). Lower time = better. All numbers are Minecraft 26.2 on Fabric.

Table 2 - server ticks

Highlights

• Chunk generation is x4.6 faster than vanilla when used alongside the optimization mods above; adding this mod to a pack that already has them makes it x2.3 faster (112 s -> 57 s -> 24 s for 3,481 chunks). With 72x structure density: 97 s -> 42 s -> 12 s.
• The big tick of the world autosave is cut from 122 ms to 29 ms (worst run 30 ms) - the save is sliced over a few ticks. The worst tick of a whole flight over new terrain: 120 ms (vanilla), 125 ms (with optimizers), 30 ms (with this mod).
• The server starts faster: 35 s -> 27 s -> 17 s from launch to "Done".
• A joining player's area is ready sooner: 58 s -> 50 s -> 26 s to load the ~2,600 chunks around them.
• The mean tick barely changes (8.0 ms with optimizers, 7.8 ms with this mod while flying): the gain is in generation speed and in the long single ticks, which are what players feel as stutter.

What it does

Three Dash Structure Optimizer makes servers and worlds with lots of structure mods faster and smoother.

Faster structure generation

• Remembers the heavy work. Structure files are prepared once and saved on disk, so the server does not redo the same job on every start and new areas generate faster. The very first start takes about 2 minutes longer while this is done; after that, starts are quicker than without the mod.
• Remembers the one-off searches. The positions of ring-shaped structure sets (strongholds and the like) are found once per world and kept on disk; the next start skips the search.
• Less repeated work while structures are placed, including strongholds.
• Cheaper terrain around structures. The terrain shaped around structures is computed from only the pieces that can reach each block instead of every piece of the chunk: bit-for-bit the same terrain, much cheaper in packs with many structures (this is where the 72x result comes from).
• Cheaper terrain generation on 26.3 on top of C2ME, zFastNoise and zFastSurface (noise sampling, ore veins, surface rules): the same blocks as the game's own code gives.

Fewer lag spikes

• Gentler world saving. The autosave is spread over a few ticks instead of freezing the server for a moment, and player files, level.dat, advancements and statistics are written off the main thread.
• Faster entity tracking. When a player moves, the server no longer asks every tracked entity whether it should now be visible: the same entities become visible in the same order, found faster in areas with thousands of entities.
• Smoother chunk loading. Chunks are sent to players a few at a time, nearest first, so flying fast or teleporting causes fewer hitches.
• Faster commands and datapacks that look up entities, such as @e[...] selectors, on big worlds.
• Less time wasted on mobs. After big block changes (a dungeon room, WorldEdit, /fill) and in very large loaded areas, the server spends less time on mob pathfinding and mob counting.
• Plays nicely with C2ME - keeps C2ME's save checks from wasting server time.
• See where the time goes. /omgopt record writes a short report of a play session: the server ticks, the slowest ticks and what they were doing, garbage collection and CPU use by thread group.

Compatibility

• Minecraft 26.2 and 26.3, Java 25. One jar for Fabric, NeoForge and Forge. Tested on Fabric Loader 0.19.5, NeoForge 26.2.0.68 / 26.2.0.90 / 26.3.0.84, Forge 65.1.2 / 65.1.3 / 26.3-66.0.12.
• No required dependencies besides the loader. It adds no blocks, items or entities: install it on the server (or in singleplayer, where it runs in the integrated server).
• Tested alongside: C2ME, Lithium, FerriteCore, zFastNoise, zFastSurface, Structure Layout Optimizer, Chunky, ScalableLux and the 58-jar structure pack above. On NeoForge it was tested with C2ME, ScalableLux, zFastNoise, Lithium, FerriteCore and Structure Layout Optimizer; for Forge 26.2 no such optimization mods exist yet, so there it runs on its own. Where another mod already hooks the same code, the mod yields (for example, with Lithium present its neighbour-signal guard is disabled) and logs why.

For modpack authors

Run /omgcache bake once and ship the resulting structure_omg_cache/ folder inside your pack. The cache keys are content-based, so it is valid on every machine with the same game version - players then start with a warm cache and never see the long first start.

FAQ

Does it change my world or my seeds? It is designed to change when and how fast work happens, not what is generated: same seed, same structures. Use the *_verify options to check on your own pack.

Is the first start slow? Yes, once: the template cache is built (about 2 minutes for the benchmark pack, on all cores). After that every start is faster than without the mod. A brand-new world also searches its ring-structure positions once.

Do I need C2ME, Lithium or other optimization mods to use it? No. It has no required dependencies besides the mod loader and works on its own.

Do I need it if I already use C2ME / Lithium? They speed up different things (terrain, ticking). In the benchmark, adding it to a pack that already had those mods cut the generation time by another 57 % and removed the long autosave tick.

Where do I report problems? Include your latest.log and the output of /omgopt status.

License and credits

MIT license. Created by DIVI4ik together with the AI agents Claude and Gemini.