What does this mod do?

This is an optimization for chests. In Minecraft, chests are tile entities, which are performance-heavy to render. This mod gets rid of that special rendering and the opening animation, which is what gives you the huge FPS boost.
Of course, this means you won't see the lid animate when you open a chest, but it's not like that animation is useful for anything anyway.

Are there any required dependencies?

None! ovo