Sodium is a free and open-source optimization mod for the Minecraft client that improves frame rates, reduces micro-stutter, and fixes graphical issues in Minecraft.
Lithium is a modern, general-purpose optimization mod for Minecraft which works to improve a number of systems (game physics, mob AI, block ticking, etc) with the goal of not changing any vanilla mechanics.
Phosphor is a Minecraft mod which works to optimize one of game's most inefficient areas-- the lighting engine. It works on both the client and server, and can be installed on servers without requiring clients to also have the mod.
Hydrogen is a free and open-source mod designed to reduce the game's memory requirements by implementing more memory-efficient data structures and logic.
