Extremely Slow VAE decode using Qwen model after the 0.3.54 update
- Dominant language
- Python
- Stars
- 133k
- Forks
- 15.7k
- Avg merge
- 1d 10h
- Merged PRs (30d)
- 153
Description
### Custom Node Testing
- [ ] I have tried disabling custom nodes and the issue persists (see [how to disable custom nodes](https://docs.comfy.org/troubleshooting/custom-node-issues#step-1%3A-test-with-all-custom-nodes-disabled) if you need help)
### Expected Behavior
Normal VAE decode speed like Flux?
This image shows Flux Krea Generation time
Flux Krea Gen time
Ksampler: 21.415 seconds
VAE Decode: 0.392 seconds
Less than 1 seconds is usually the speed of vae decode process
### Actual Behavior
After the ComfyUI 0.3.54 update
Why only Qwen VAE decode is this slow? the very same resolution as above?
If I use Nunchaku Qwen Image fp4 4 steps model, my Ksampler generation time is 4.8 seconds, my VAE decode time is 3 seconds! Almost identical to the ksampler speed? How?
It wasnt this slow before?
Qwen Image Fp8
Qwen Image Fp8 gen time
Ksampler: 54.697 seconds
VAE Decode: 3.851 seconds (almost four times slower than Flux)
Nunchaku Qwen Image with 4 Step Lightning
Qwen Image Nunchaku 4 steps gen time
Ksampler: 4.472 seconds
VAE Decode: 2.151 seconds
### Steps to Reproduce
Just test with the sample workflow from templete, After the ComfyUI 0.3.54 update
### Debug Logs
```powershell
model_type FLUX
Requested to load Flux
loaded completely 16174.2524269104 122.3087158203125 True
100%|██████████████████████████████████████████████████████████████████████████████████| 20/20 [00:08<00:00, 2.28it/s]
Requested to load AutoencodingEngine
loaded completely 8814.538383483887 159.87335777282715 True
comfyui lumi batcher overwrite task done
Prompt executed in 19.60 seconds
got prompt
Using pytorch attention in VAE
Using pytorch attention in VAE
VAE load device: cuda:0, offload device: cpu, dtype: torch.bfloat16
Using scaled fp8: fp8 matrix mult: False, scale input: False
CLIP/text encoder model load device: cuda:0, offload device: cpu, current: cpu, dtype: torch.float16
Requested to load QwenImageTEModel_
loaded completely 22496.484112548827 7909.737449645996 True
model weight dtype torch.float8_e4m3fn, manual cast: torch.bfloat16
model_type FLUX
Requested to load QwenImage
loaded completely 22016.08407058716 19483.948791503906 True
100%|██████████████████████████████████████████████████████████████████████████████████| 10/10 [00:27<00:00, 2.79s/it]
Requested to load WanVAE
0 models unloaded.
loaded partially 128.0 127.9998779296875 0
comfyui lumi batcher overwrite task done
Prompt executed in 47.25 seconds
got prompt
Requested to load QwenImage
loaded completely 28597.275080108644 19483.948791503906 True
100%|██████████████████████████████████████████████████████████████████████████████████| 10/10 [00:27<00:00, 2.79s/it]
0 models unloaded.
loaded partially 128.0 127.9998779296875 0
comfyui lumi batcher overwrite task done
Prompt executed in 34.41 seconds
got prompt
Using pytorch attention in VAE
Using pytorch attention in VAE
VAE load device: cuda:0, offload device: cpu, dtype: torch.bfloat16
Using scaled fp8: fp8 matrix mult: False, scale input: False
CLIP/text encoder model load device: cuda:0, offload device: cpu, current: cpu, dtype: torch.float16
clip missing: ['text_projection.weight']
Requested to load FluxClipModel_
loaded completely 29205.675 4903.231597900391 True
Using scaled fp8: fp8 matrix mult: True, scale input: True
model weight dtype torch.bfloat16, manual cast: None
model_type FLUX
Requested to load Flux
loaded completely 22883.44331436157 11350.088394165039 True
100%|██████████████████████████████████████████████████████████████████████████████████| 20/20 [00:19<00:00, 1.03it/s]
Requested to load AutoencodingEngine
loaded completely 4173.6408767700195 159.87335777282715 True
comfyui lumi batcher overwrite task done
Prompt executed in 29.06 seconds
got prompt
Using pytorch attention in VAE
Using pytorch attention in VAE
VAE load device: cuda:0, offload device: cpu, dtype: torch.bfloat16
Using scaled fp8: fp8 matrix mult: False, scale input: False
CLIP/text encoder model load device: cuda:0, offload device: cpu, current: cpu, dtype: torch.float16
Requested to load QwenImageTEModel_
loaded completely 29205.675 7909.737449645996 True
model weight dtype torch.float8_e4m3fn, manual cast: torch.bfloat16
model_type FLUX
Requested to load QwenImage
loaded completely 22764.77462615967 19483.948791503906 True
100%|██████████████████████████████████████████████████████████████████████████████████| 20/20 [00:51<00:00, 2.57s/it]
Requested to load WanVAE
0 models unloaded.
loaded partially 128.0 127.9998779296875 0
comfyui lumi batcher overwrite task done
Prompt executed in 65.60 seconds
```
### Other
_No response_
Contributor guide
Assessment
This issue has not been assessed yet.