I have found turning off displacement, glossy, and reflections make the light cache and irradiance maps quick. My question is, what is lost in doing it this way? If nothing, then why isn’t this an automated thing? Once I hit render couldn’t glossy, reflection, and displacement be disabled, everything gets calculated, turned back on and rendered for the final.
It depends on how large is the displacement - if you are using it to create a landscape, then obviously the results of GI with and without it would be fairly large. Same for glossy reflections - the results that you get are generally different and V-Ray has no immediate way of knowing whether this difference will be significant or not.
Best regards,
Vlado
Typically, my displacement is stone, siding, and roof, which is generally really small. I rendered out one normally and one pre-calc, and they are virtually identical. The pre-calc for a clean render takes second when I turn reflection and displacement off. With them on, it can take an hour.
on this one, the first one wasn’t pre-calculated, but the second one was.