In Cycles Preview (not rendering the image), my GPU is 20 times faster than my CPU, but only twice as fast in Rendering! The GPU and CPU speed, as stated, is compared in Preview mode, so if there was any thing that would weight it down in the actual render then it would affect both CPU/GPU basically the same (I think).

$500 GPU! - GTX 1060 (6GB), CPU - i7-6700

I tried tile size at 256 x 256.


1 Answer 1


CPUs work better when using tiles, escpecially smaller tiles. While GPUs work better when using bigger tiles or in the case of preview, 1 tile the size of the whole image. So when previewing it's just like one big tile, and that's why the GPU is much faster. and when rendering, it uses small tiles, and that's why the CPU performs better when rendering.

  • $\begingroup$ Oh yes GPUs are parell.............it now seems (in a zoomed in shot of the big ball design without white background) that for either preview or render the GPU is possibly 6 times faster........but what floors me is how when I was zoomed out the CPU went 1, 2, 3 each second while the GPU got up to like 10 after the first second. $\endgroup$ Dec 2, 2016 at 11:07
  • $\begingroup$ So does it mean that when pressing the Render button, the tile size should be equal to the final resolution when using the gpu? $\endgroup$ Dec 2, 2016 at 13:41
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    $\begingroup$ @FacebFaceb no the render tile should be some fraction of the total render size. You have to make tests to find the optimal size for your System or a particular Scene $\endgroup$
    – user1853
    Dec 2, 2016 at 15:04

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