Huge render slowdown in 2.77

Support Lighting and Rendering
1

I was placing comments in the main development thread but perhaps its best to do it here. I have copied the info from my other post:

I am also having TDI events now with 2.77. I have opened an existing blend and when I enabled the rendered view lender crashes with a timeout on my gtx 980 ti.

I’m running windows 10 and am downloading the newest drivers now.

Edit:

there seems to be a rendering issue with 2.77.

I tried to f12 render the same project and the render slows down and only renders 1 sample for the tile every 2 seconds or so. The render was nearly hung at 3 min in and only about 1/3 complete. I finally does complete and takes over 9 min to render at 120 samples.

I opened the same blend in a copy of 2.75 I have saved and it renders the complete image in 2:16.

I removed 2.77 and installed 2.76b and it renders in 2:33

At this point I doubt that hardware drivers are the issue.

It seems there is something going on here. Any ideas?

2

there is a link to the blend

https://drive.google.com/file/d/0B4rqfTwu09IQQjFIT2dFakIyc0E/view?usp=sharing

3

Yup, i confirm a HUGE slowdown (cc. 350%) on GPU with blender 2.77. At least with this scene. I suspect merging of the code from previous experimental feature set. Got no time to research further.

4

mib2berlin was kind enough to point out that others have reported this to the devs prior to release.

Here is a thread about it https://developer.blender.org/T45093

5

I don’t know if this is related, but I noticed on my machine (which I use CPU because I don’t have a good GPU on my laptop) that a render took about 8:10.83 to complete (Blender 2.77, Win 2010, 64 bit, AMD A8-3520M). I also noticed that it was doing the render in a spiral pattern (Hilbert Spiral). I’m guessing this is now the default, because I didn’t change anything in that part of the render tab on a brand new project that I had started about 3 hours ago.

I remembered hearing about slow downs on renders in 2.77, but hadn’t really investigated it. I switched the setting back to Center, which is what I had been using in 2.76. The time on that was 4:33.50. The pattern is the ONLY thing I changed, and you can see the difference in the render time.

As I said, I’m not sure if this is related to the same render slow downs others are experiencing, but it might be worth taking a look at.

6

I’m having NON-RENDER slow-downs in 2.77 with a complex scene: http://www.pasteall.org/blend/41205

This one slows down the ENTIRE COMPUTER. If I hover the mouse over the Outline window, on Mac I get the “spinning pizza of death” for 2 seconds, every 4 seconds. This cycle NEVER STOPS. Worse, this happens to EVERY ASPECT of the entire operating system, including all other applications. If I quit Blender (or force-quit which is more likely) the entire computer remains FROZEN for several minutes.

I opened this scene with 2.76b, and none of these problems exist. (Yes, it’s a bit clunky because of the number of objects, but NOTHING like in 2.77.)

It would be really helpful if someone could test this scene in 2.77 on non-Mac platforms …

7

Hi, this file is unusable even in 2.76b with my system (specs in signature)
I join all objects to one and all run smooth now (joining need a several minutes!).

Cheers, mib

8

mlb2berlin: Thanks for testing! Noob question: I don’t think rigid-body will work as expected if all objects are joined, right?

9

How do you change the render tile pattern ?

10

Nevermnind…i found it :slight_smile:

11

Not sure if this is the problem or not but the samples are in 2.77 by default 120, in the old version they were 20. That could be why it’s so slow.