lightpath node : ray roughness

In order to optimize render time, an additonnal ray information is needed : Ray roughness or Ray "radius"

With this information, a shader could be build so that Long rough ray could use a baked duffuse texture or simplified version of the shader, or smaller resolution hdr.

It could be just a ouput slot on the lightpath node giving the raw roughness value of the shader it's originating

Or ray radius at the point of shading, so it could also serve to optimize depth of field.