SwiftGen

Faster world generation. SwiftGen remembers lookups that worldgen repeats and batches bookkeeping; the chunks that come out are block for block the ones you would get without it, with any combination of its switches. It runs where the world is generated: in a singleplayer game or on a dedicated server.

Caches

• Biome lookups by position (structure placement checks, /locate, explorer maps, the world-spawn search) are remembered per generation thread, 4 096 entries by default, so the climate calculation is not run again for each one.
• Block reads and writes during feature placement reuse the chunk they last touched.
• The noise fill skips its two heightmap updates per placed block and fills both heightmaps in one pass afterwards.

ReTerraForged

• ReTerraForged remembers one position per thread for its point lookups, so structure placement, /locate and the spawn search rerun its whole terrain calculation for nearly every check.
• SwiftGen widens that to 4 096 cells per thread. The values come from ReTerraForged's own code.
• This part only acts when ReTerraForged is installed. The other caches work on any world.

Stats command

• /swiftgen stats prints milliseconds per chunk for the noise, surface and decoration stages, the hit rate of each cache and the chunks generated per minute. It needs operator rights.
• /swiftgen reset zeroes the counters, for example before a pre-generation run.
• One run on one ReTerraForged world, 5 727 chunks: noise fill 33.85 ms a chunk, 87.1% hits on the region cache, 99.1% on the ReTerraForged cache, 3 649 chunks a minute. It is a single run on an unrecorded machine, not a before-and-after benchmark.

Requirements

Minecraft 1.20.1 (Forge or Fabric), 1.21.1 or 26.2 (NeoForge or Fabric), on Java 17, 21 and 25 respectively. The Fabric builds need Fabric API. Install it where the world is generated: on the server, or in your singleplayer game. ReTerraForged is optional. Every cache has its own switch in config/swiftgen-common.toml, or config/swiftgen.json on Fabric.

This mod has been abandoned. It works fine, but it will not receive updates.

The other performance mods

NeoForge 1.21.1 and 26.2, Fabric 1.20.1, 1.21.1 and 26.2, Forge 1.20.1. On the server or in singleplayer. Free to use in modpacks.