so, I've been trying to render clouds using Cycle's Volume Scatter node in a way that doesn't murder render times. Plugging Volume Scatter into the Volume option of a Material Output, works fine, render times aren't that bad, and increase like you would expect them.
Plugging in the factor of a texture into the density part of Volume Scatter, however, absolutely destroys render times. Render times jump from 0.92 seconds to 6.52 seconds for a low resolution 8 sample scene. Presuming it doesn't crash, 95% of the time if I try to render it out, Blender will just give up and crash. I've seen this on GPU and CPU, a GTX 970 with 4GB of VRAM, and a 4790K with 16GB of RAM, respectively.
I'm running Blender 2.78c, is this just an issue with volumetrics at the current time?