Raymarcher Setup renders with Vray extremely long!

[sitnisati]

Hello,

There are other two very important parameters:
- Step size
- Shadow samples

It seems that you have a very thin smoke, so you can try to use step size 5 or so and 10 shadow samples.
Not sure how your scene looks like, but I think you might also lower Noise Levels to 3 or 4.
I hope this helps.

Kresimir