Originally Posted by LucentDreams
I'm curious as to any cases in where the old physical methods would be faster than embree. I mean if there is an option what is the option there for? do the results differ notably, as they don't appear to, so are there cases where embree might strain compared to the old method, or limitations?
There are rare cases where the old method is faster than Embree. The main reason to keep the old method is its lower memory footprint. Scenes that push your RAM boundaries with the old method could run into problems with Embree.
There are three methods to choose from, Embree (Faster), Embree (Smaller) and Physical.
Physical has the lowest memory footprint, Embree (Smaller) up to 15-20% higher and Embree (Faster) up to 30% higher memory usage. The speed gain is well worth it though IMO.