Caesium (Forge)
Caesium is a general-purpose optimization mod and unofficial fork of the Fabric mod Lithiumfor Minecraft Forge. This mod aims to optimize the general performance of Minecraft(mob ai, physics, chunk loading, etc..) without changing any behavior. It works on both the client and server, and can be installed on servers without requiring clients to also have the mod. With the mod installed, you can see on average a 45% improvement to server tick times, resulting in a much leaner game.
Even in single-player, your game runs an "integrated server" which ticks the world your player is in. Through optimizing the server-side of the game, this can free up your computer's processor to focus on other tasks, resulting in improved frame rates and responsiveness. For multiplayer servers, administrators can expect a sizeable improvement to tick times, allowing their hardware to support more loaded entities, chunks, and players.
Installation
Caesium only supports Minecraft Forge 1.16.5, So make sure you have the latest version of Forge present and simply drop the mod into your mods folder, no other mods or additional setup is required!
Modpack Permissions
Much like Lithium, this is a free and open-source project on CurseForge, and as such-- of course you can include it in your modpack!