OptiFine

OptiFine is a performance mod created by sp614x. The classic Minecraft optimization and shader mod adding HD textures, dynamic lighting, shader support, and performance settings. As a performance mod it concentrates on frame rate, loading times, and memory use, and it has been downloaded around 350 million times, which puts it among the options players reach for in this space.

OptiFine is built for players who want shaders, connected textures, and tuning in one familiar mod. OptiFine bundles performance options, shader support, connected textures, and zoom, and remains the classic all-in-one client enhancement. It is approachable enough to drop into a world and use right away, with little setup required.

The mod is available exclusively for Forge. It currently supports Minecraft 1.20.1 and 1.21.1, spanning the 1.20.1 to 1.21.1 releases. It is a client-side mod, which means you can add it to your own game for personal benefit even when the server you join does not run it.

OptiFine works particularly well alongside MrCrayfish's Furniture Mod. It targets the Forge side of the ecosystem, so it fits comfortably into Forge and NeoForge packs.

As a performance mod, OptiFine is meant to improve how the game runs rather than change gameplay, so it is generally safe to combine with other optimisation mods.

If you are comparing options, similar mods include Sodium + Iris and Embeddium + Oculus. They cover comparable ground, so the right choice usually comes down to your loader, version, and the rest of your pack.