Is Sulphur-2 just slower than LTX 2.3?

#50
by Zenshuuin - opened

So I've been using RuneXX's LTX 2.3 workflows (https://huggingface.co/RuneXX/LTX-2.3-Workflows). I like that these cover a number of different use cases besides just T2V I2V. There's also FLF2V, and video extension workflows. I was hoping since its based on the LTX 2.3 pipeline, I would be able to just plug Sulphur-2 into these workflows.

I tired downloading sulphur_dev_fp8mixed.safetensors and ltx-2.3-22b-distilled-lora-1.1_fro90_ceil72_condsafe.safetensors and using them in the RuneXX workflows.

I was able to generate a decent video clip, but it was MUCH slower than with the LTX 2.3 models

A clip that on ltx-2.3-22b-distilled-1.1_transformer_only_fp8_scaled.safetensors took only 5-10 minutes, took over an hour and a half using the sulphur-2 models.

So, I'm wondering if I'm missing something. Is there some tweak I can make to get the workflow running faster, or is this model just a lot slower than the ltx 2.3 model I was using?

I just use the comfyui template for ltx 2.3 for t2v, i2v, flf2v.
Then switch the model and lora to the sulfur ones.
Windows 10, RTX 5090 with 64GB DDR5 System Memory

15sec duration same prompt and seed.
t2v sulfur slower at 173.48 vs 161.09
i2v sulfur faster at 162.13 vs 167.22
flf2v sulfur slower 174.14 vs 168.41

Id call that with in the margin of error.
That big a difference you are getting is like the difference between fitting in system ram and having to use the page file.

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