Now the same geometry and camera are shared between full-screen quad instances. A mesh is still created for each full-screen quad instance since that avoids repeatedly setting the material on the mesh in cases where a pass only needs one material.

The quad can be passed to renderer.render() directly without being a part of a scene.

This deduplicates a lot of code that used to be the same in a lot of postprocessing passes.

"Delta" is generally used to just mean change. The previous name didn't make it clear what was changing.

Also calculate deltaTime automatically in EffectComposer in case it's not provided.