Cycles GPU Render Times

Hi, I was having some slowness with Cycles so I did some research and found that I needed to enable GPU rendering for any significant increase. After a little more reading I found that my GPU, a GTX 1080, had one of the best compute compatibility scores as described by Nvidia. After seeing that and reading some responses saying that people were seeing 4 to even 10 times the difference in rendering times I was highly optimistic that I would see a big change…

However, after a couple test renders I was sorely disappointed. In fact, at first I couldn’t even tell if it was even making a difference, but after careful review a simple scene with a plane and a monkey head with subsurface scattering my scene will render at 32 seconds with GPU and 41 seconds CPU. Does that seem right? I was kind of expecting the results to be around half of what they were with GPU.

You have to make sure your tile size is set appropriate for GPU rendering on the performance tab of the render panel.

CPUs like small tiles (e.g. 32x32) whereas GPUs like larger tiles (e.g. 256x256).

Sometimes GPUs even like the same ratio as the display ie 16:9 (tiles of 512x288 or 256x144 work for me and depend on available memory on the card as well), and of course the real benefits show in scenes of more complexity.

As others have alluded to, out of the box settings for GPU rendering are not optimum. You need to set up your render settings properly.