Excessive Render Time / Path Tracing Enabled

[RichTwo]

Hey, all.  I've taken quite a long break from Terragen, but decided to give it a go at least once more. Both images are identical except one was done using path tracing. That one took over three hours to complete. The other without took only a little over 30 minutes. I had 3 populations: Dune's Grass 26 and two Xfrog trees. I have all the latest updates of TG, checked all settings including atmo optimization. 1st question: which is a better quality?  2nd: I've tried path tracing before, and it added maybe 15 minutes. I'm not going tell you which is which just yet. I've posted images with populations before and was called out because it was evident that I didn't use PT. Have look see at the  .tgd please, it's got to be something, like before I simply couldn't see. Thanks in advance.

[Doug]

Hi, im to new to tell whats what, so i just rendered the pic
the one you see is Path Tracer On 19:40
Standard Render is 1:47

[Dune]

First; with such scarce greenies I wouldn't use PT. You can see the big one is PT only by the denser shadows in the tree centers and in the bases of the grass, but I don't even know if I find that better. If you need more darks you can also alter the GISD settings a bit; increase occlusion weight to say 1.5, and/or the radius to say 32. Needs some experimentation.
Second; your file is extremely complex for the effect. Lots of shaders/nodes that need to be calculated. It looks like you put it together from tgc's, but my advice would be to build something like this from scratch. It can be done much simpler, IMO. Especially everything before a compute terrain (and some merge shaders) takes its toll.
Third, what's the main input to the fog layer doing there? It won't do anything as far as I can tell.
Fourth; micropoly detail can easily be set to 0.5. Saves a bit of time again.
It's a great terrain, but it would be interesting if you could try to mimic from scratch and see how that works. Use a PF masked strata shader instead of the complex blue setup, use less colors....
Oh, and it's good to see you back!

ps. it rendered in RT in 15mins on my machine, with detail at 0.5.