Lithium (Fabric/NeoForge)

Lithium is, among other things, a general-purpose optimization mod for Minecraft. It tries to improve various areas of the game without altering any core vanilla mechanics. Thus, it works both on a client and on a server, and having it on servers doesn't require someone having clients install it.

Performance in Lithium is improved by optimizing the internal game server, used for 'ticking' the world. This frees up the computer's processor and allows it to do other things, enhancing the frame rate and responsiveness. The tick time on multiplayer servers should see a greatly improved rate: the hardware can handle more entities, chunks, and players. This is an exact behavioral mod with vanilla and should work with almost any Minecraft server running Fabric, even for complex gameplay scenarios or creations.

Lithium is officially allowed in Minecraft speedrunning due to the strict adherence to vanilla mechanics.

Lithium uses a somewhat unconventional configuration system that allows for the enabling/disabling of patches this mod applies. This allows fine-grained control as to what code in Minecraft is modified by Lithium to help track down and eliminate bugs or mod incompatibilities the mod may cause. An empty configuration file means that default options are utilized, set up for the best performance.