Blender 4.0 dreadful Metal GPU performance #113847

New Issue

Steve Jarratt · 2023-10-17T16:29:36+02:00

Steve Jarratt commented

2023-10-17 16:29:36 +02:00

System Information
Operating system: macOS 14.0
Graphics card: W6800X Duo

Blender Version
Broken: 4.0 Oct 17, bbf87ee78c
Worked: 3.6.4

Short description of error
When rendering Blender benchmark scenes, the latest build of Blender 4.0 shows dismal Cycles performance with GPU rendering.

Exact steps for others to reproduce the error
Load the Classroom scene into Blender 4.0 and render with Metal GPU (W6800X Duo in my case). The render time was 2:48 compared to 29 seconds in Blender 3.6.4! It's almost as slow as using the CPU. Something is drastically wrong – I tried the Barbershop scene and it was similarly slow, with an expected render time of over 20 minutes!

Rendering in 3.6.4 is fine, and the UI is fairly responsive with Cycles rendering turned on n the viewport. But Blender 4.0 is an order of magnitude slower. Please see the render times in the accompanying screengrabs…

**System Information** Operating system: macOS 14.0 Graphics card: W6800X Duo **Blender Version** Broken: 4.0 Oct 17, bbf87ee78c42 Worked: 3.6.4 **Short description of error** When rendering Blender benchmark scenes, the latest build of Blender 4.0 shows dismal Cycles performance with GPU rendering. **Exact steps for others to reproduce the error** Load the Classroom scene into Blender 4.0 and render with Metal GPU (W6800X Duo in my case). The render time was 2:48 compared to 29 seconds in Blender 3.6.4! It's almost as slow as using the CPU. Something is drastically wrong – I tried the Barbershop scene and it was similarly slow, with an expected render time of over 20 minutes! Rendering in 3.6.4 is fine, and the UI is fairly responsive with Cycles rendering turned on n the viewport. But Blender 4.0 is an order of magnitude slower. Please see the render times in the accompanying screengrabs…

Screenshot 2023-10-17 at 2.41.12 pm.png

6.8 MiB

Screenshot 2023-10-17 at 2.44.34 pm.png

8.9 MiB

Steve Jarratt added the

labels 2023-10-17 16:29:36 +02:00

Pratik Borhade commented

2023-10-18 06:13:32 +02:00

Hi, thanks for the report. I suspect this is related to #112596. Can you confirm?
I don't have similar hardware to verify the performance difference.

Hi, thanks for the report. I suspect this is related to #112596. Can you confirm? I don't have similar hardware to verify the performance difference.

Pratik Borhade added

Status

Needs Information from User

and removed

Status

Needs Triage

labels 2023-10-18 06:13:42 +02:00

Steve Jarratt commented

2023-10-18 11:58:43 +02:00

Yeah, the case #112596 sounds much the same. Render speeds are anything from 200% slower to 500% slower in 4.0.

I opened the junkyard scene and hit F12 – Blender 3.6.4 = 16.31 seconds; Blender 4.0 = 34.38 seconds.

Yeah, the case #112596 sounds much the same. Render speeds are anything from 200% slower to 500% slower in 4.0. I opened the junkyard scene and hit F12 – Blender 3.6.4 = 16.31 seconds; Blender 4.0 = 34.38 seconds.

Screenshot 2023-10-18 at 10.54.51 am.png

3.8 MiB

Screenshot 2023-10-18 at 10.56.01 am.png

3.3 MiB