Anyone knows why it rendered faster and sometimes it rendered even slower than CPU, the speed of GPU rendering is not so constant, any ideas?
Think you’ll more answers if you post the questions in the help & troubleshooting category.
But I think I also once had a weird long render time with GPU, but if I recall correctly that was also a really big image I was rendering. And I’m not sure where you will use your image but it’s size is now 65 x 115 cm at 300dpi. But still, with that much white it shouldn’t really take long. I’ll do some tests myself as well with really large renders to see if that might be a problem.
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Hi Ankushk,
For the topic starter it was mainly the incredible high resolution. I did notice something like this some time ago and I have the idea it was because it moved the camera way closer to an object that had a displacement map. I also notice it sometimes when I have transparent parts and I render from a different angle than earlier. I think it basically can take longer to do the same amount of samples if it has to calculate more bounces suddenly because the angle compared to the light source changed.
This is just guessing by what I see what happens and trying to find some own logic. Not sure if it’s actually the reason behind it.
I have experienced the same thing. From what I have been able to find, it generally renders slower when using the render queue vs a single rendering. Not sure what that is, but most of the time it isn’t a huge deal, but for more complicated things with a lot of transparency, the difference can at times by 10x in duration.
The situation that I met is they are totally different when you render two products almost the same, the same environments, the same materials, the same image styles, and the same rendering modes, and I don’t know why.
But in your opening post you render an image of more than 7000x13000 pixels. That’s a lot 
Anyway, sometimes it is really strange as it took only a few secs to render a 19201920 while took hours to render a 32803280
I don’t really know the reason why it performs like this, in recent days, it much quicker than before as it take only a few secs to render a 1920*1920, but it still needs hours to do a scenario rendering, and my GPU is 3070Ti, 8G. Anyway, I think it is enough for my daily work, except I need to do some large scenario renderings.
Well it isn’t just the size of the render, but how much geometry in the scene, the lighting and ray bounces, depth of field, caustics, and many more things that factor in making a render longer. It will be a lot faster to render a more simple scene without complicated lighting.
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emmm… the factors that you mentioned actually do affect the time of rendering, I need more time to figure out the connection between them, anyway, thanks for your advice.