Cullium is a lightweight client-side performance mod that stops Minecraft from wasting time rendering things you can't see anyway.
Vanilla Minecraft still processes invisible entities through a large chunk of the render pipeline even though nothing shows up on screen. In servers or worlds with lots of invisible entities this adds up fast. Cullium cuts that work out completely.
This is a client-side only mod — it does not need to be installed on the server. Should be compatible with most other mods.