Do we know how long it takes to create render elements? Does any one take any longer than another, or are they all the same and take no more time to create. I know extra texture can add 10% to your render times, but what about z-depth, reflection, or any of the other? if I don’t use most of the ones I create, does it make sense to just omit them, or does it not matter?
any additional buffer adds time. Some more then others, for example zdepth will take a small hit but not as bad as extra tex. I typically only output the ones I need. Also, just adding render elements makes vray use more ram and takes slower then having them disabled so having bare minimum is best.
Okay, good to know.
I have been working on a scene and over the past week my render times, for the final output, was 6 hours. I just removed the 6 render elements I had and it is now less than 2 hrs. I had the basics, plus two extra textures.
if you have consider for antialiasing on in the extra tex, this will slowdown your rendering but really it shouldn’t be 6-2 hours as this sounds a bit too extreme.
I had two extra-textures with V-Ray dirt in one and Rich dirt in another. I had reflection, refraction, two light selects, plus the other typical ones. Honestly, I usually only use the extra textures and maybe the reflection. Sometimes, if it works, I use the light selects (sun/sky). I’m rendering out one now, without any render elements, and it’ll be a little under 2 hours.
2 hours with a lot of displacement, both 2D and 3D, Forest Pro grass, all at 5100 X 2870.
light selects take forever, they essentially render the image twice. I only use them on low res tests initially if I want to play with the lighting balance, then once i’ve got it figured out i go back into max and match what i’ve done for the final render.
So, I guess two is insane 
that’ll be most of the reason why you went from 6 to 2 hours, yeah - your base and each of those took 2 hours a piece.
well a few ambient occlusion passes will most certainly also add to render time. Typically you don’t need ao in architecture (some people use it) but its really not necessary. The need of AO means lack of texture/surface detail so people use it to push those effects more.
I find that I can render with lower settings and get the fine detail with the AO. However, I can render an AO fast with a light material and GI off.