Thanks Danny. I'm testing your file now and would like to split this discussion out into its own thread. I'll do that once I have some tests done. By the way though, when testing between major versions like this it's almost always better to create the scene in the earlier version (TG 2 in this case), then load it in the later version, because TG3 has features and settings that TG2 does not, and TG3 is backward compatible while TG 2 has no knowledge of the existence of TG3 or its settings. So what you'd ideally want to do is create the file *in TG2*, then test in TG3. That being said it doesn't necessarily explain the results you're seeing.
I also want to mention that your settings are, well, a bit insane quite frankly. AA8 with Defer Atmo/RTA is seldom advisable, but *especially* with 24 atmo samples and Quality 1 for clouds. It's no wonder that Defer/Raytrace is so much slower here. Oh and there *is* GI since the Enviro Light is enabled and GI Det/Qual are 2 and 2. Perhaps you meant GI Surface Details? But that doesn't affect the atmosphere at all anyway.
Edit: these posts have now been split off into their own thread.
- Oshyan
