Using the new GI with GPU enabled I rendered the below image in 6 minutes on a notebook PC with a GTX 765M. The leftover noise is from portal lights. (A higher powered machine with a K6000 and more CPU cores renders this scene in less than 3 minutes for the frame)
The new GI is a brute force technique with many improvements to regular brute force rendering including better filtering control. The below image does not use the filter and instead renders as-is.
This feature is not finished and I used “diffuse” paths as it is most complete and fast. You can also render using the same method on the CPU. If you’re curious why it presamples the scene, it is because custom and CPU shaders cannot be rendered automatically on a GPU. Presampling allows you to render legacy scenes without changes if the scene contains supported effects.
There are features not currently supported by this technique since it’s not complete. More conversation and examples will follow. Consider this experimental for now. Begin testing it along with other users, look here.