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I have a scene in which I added some smoke to enhance an object's movement. As the scene is set in the clouds I have a lot of volume shaders, which I have had no problem rendering. After adding the smoke I noticed render times go from around 30 seconds per frame to about 50 minutes, and has made the rendered viewport shading unusable. I don't have any problem when not using the density attribute of the smoke simulation (obviously it won't work without it and will just render the domain).

Is this just a limitation with Blender or my hardware? Is there a way to speed up the render? I would rather a faster render time with less photo realistic results if possible.

I am using Blender 2.77a and am rendering with a GTX590 (have tried with CPU rendering and see similar increases in render times).

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  • $\begingroup$ I'm not sure but I believe that happens due to 3d texture being more computationally difficult to render than uniform volumetrics (not using density attribute). You may somewhat improve the performance by reducing light bounce count, but ultimately there is not much you can do to speed up rendering the smoke. $\endgroup$ – Mirac7 Apr 10 '16 at 13:07
  • $\begingroup$ The smoke makes it take years? yikes. What version were you using when you started your render? You might try updating to a newer version that has been released in recent months - I've heard they are much faster then the versions from 2015-2016, $\endgroup$ – X-27 is done with the network Feb 24 '17 at 16:28
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One thing you can try to speed up smoke rendering is by reducing the volume sampling step size.

enter image description here

The default value is great for rendering super-high resolution smoke, but I find that a larger value often works fine and gives you a 2-4x speedup at virtually no quality loss.

enter image description here

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