Don't Render Entities That Are Blocked From View (Entity Culling)

Minecraft can seem good for performance because of how simple the Simple/Fancy graphics are. But its actually not. One of these biggest resource hoggers is the fact that the game renders entities even if they are behind bigger entities or blocks. For example, if you are above an ancient city structure, a warden could spawn, and do all its special effects and stuff. Plus wardens are one of the most resource demanding entities in Minecraft. Performance on all devices would be much better if this was introduced.