Ok, another test. The only thing that changed is the second buddha and the room material is no longer the default glossy white, but a matte with an off white almost yellow color. This sped up the render significantly.
I think next I may try to have the AO map control the roughness so the darker areas are less smooth.
Ok, forget everything I just said about the inverted AO map. Just make a new mix texture set to greyscale and use the normal AO map to control the mix. then you can change the amounts of each slot as you see fit.
Here is the result from that.
And here is the mix setting that got me this result.
patina_mix.jpg (18.86 KiB) Viewed 1271 times
The bottom number controls the brighter areas on the AO map, and the top number the duller areas. 0.0 is the most shiny, and 1.0 is a super matte. Even 0.5 is almost completely matte.