Problem Rendering Certain Frames of Short Animation

Having an issue animating the attached file.

The first 44 or so frames render fine (GPU) in 15 to 20 minutes with using single GTX 970 but frames 45 and 50 were taking well over an hour. Frame 60 on the other hand was typical of the first 44 frames.

Any idea what is going on?

I had hoped to render this character in a short film complete with environment but am concerned that something is seriously wrong with the model or there are hardware limitations that will make making this short film impossible.

Any help would be much appreciated.

Note that I am using an add-on “orient_custom_shape_v2” in the model.



STUDIO_SCENE.blend (3.9 MB)

Whenever I read something like: “… but frames X render slow…” then the first thing I see is that if user are using Motion Blur. Sometimes the problem is a bug, other times it is just how Motion Blur works in Blender.

What version of Blender do you use? What Operating System?

My test with only 10 samples, GPU (GTX 960), Blender 2.79 official.

*Frame 10:
Motion Blur ON: 00:15.84
Motion Blur OFF: 00:11:12

*Frame 45:
Motion Blur ON: 00:38.28
Motion Blur OFF: 00:11.06

I’m not sure if you get about the same difference using only 10 samples.


Thanks for the quick reply.

Was originally 2.79 but updated to 2.79a this evening after the problem was noticed with no improvement unfortunately. Computer and OS are per my signature - this computer was built a few years ago for rendering and is not used every day so OS is still Mint 17.1 with only periodic, critical updates.

Motion blur is indeed on and something that I want to keep in order to have a cinematic look.

Any suggestions for improving performance or why some frames are substantially longer to render than others?

Thanks again.

I do not know much about motion blur, I do not use it because of the slowness (I do not have good hardware anyway), and many times it has not been possible to know if this kind of problem is due to a bug or just Motion Blur design. For example, a similar problem:

So you could open a new report there to see what developers say (under BF Blender on the top left, Report Bug button):

You indicate in detail the information that you are requested when you create a new report.