SwiftGen

World generation, faster. The chunks that come out are identical to the ones you would have got without it.

 Same seed, same world. Every option, in any combination - none of them change what generates, only how long it takes. 

Where the time goes

Biome lookups, block access during feature placement, and heightmap bookkeeping all get done over and over when they could be done once. SwiftGen remembers the answers.

ReTerraForged

If you use RTF, this is the reason to install it. RTF remembers exactly one position at a time, and structure placement jumps all over the map - so nearly every check re-runs the entire terrain calculation for a single point. That is why creating an RTF world and running /locate both feel like the game has frozen.

SwiftGen remembers a few thousand instead of one. RTF is not bundled, and the whole thing is inert without it.

Measure it

/swiftgen stats prints per-stage timings and cache hit rates:

  noise fill    33.85 ms/chunk     rate  3649 chunks/min  
  region chunk cache   87.1% hits                         
  RTF point-cell cache 99.1% hits                         

That is one run on one world, not a before-and-after benchmark.

Setup

Side      both - it runs on dedicated servers
Config    swiftgen-common.toml
Commands  /swiftgen stats, /swiftgen reset

The rest of the series

NeoForge 1.21.1 plus Fabric and Forge builds. Runs on the server as well as the client. Free to use in modpacks.