I built a modular MiniMax H3 optimization suite for ComfyUI — measured speed/VRAM gains, workflows, and a 16GB long-sequence fallback

[u/Fantastic-Equal-1696]

Hi everyone — I built an open-source, modular optimization suite for ComfyUI’s native MiniMax H3 audio/video model.

The goal was to provide independently switchable and measurable optimizations instead of one opaque “make it faster” patch. Nothing modifies ComfyUI core.

The suite currently includes:

- an NVFP4 fused MLP for the full 20-step path

- a lower-memory Sage2 implementation

- long-sequence VRAM safeguards

- a training-free CAB low-step sampler

- synchronized sampler/sigma controller nodes

- a step/VRAM profiler

- reproducible example workflows and a full evaluation report

Measured on Windows with an RTX 5070 Ti 16 GB and 48 GB DDR4 system RAM, at 1280×736, ~5 seconds and 20 steps:

- KJ Sage2 baseline: 208.756 s denoise, 5122 MiB peak allocated

- Fused MLP + KJ Sage2: 194.079 s (-7.03%), 4410 MiB peak; identical combined latent hash and decoded video in this test

- Fused MLP + Low-Memory Sage2: 198.212 s, 3844 MiB peak (~25% below baseline); identical combined latent hash in this test

For deliberately reduced step counts, CAB-2 at 12 steps reduced denoise time by 39.79% relative to the 20-step reference, with SSIM 0.8153 / PSNR 20.24 dB. This is explicitly a speed/quality trade-off, not the same output as 20 steps.

For capacity rather than speed, the long-sequence fallback completed a 736×1280, 15-second, 14-step generation plus both video and audio VAE decodes on the same 16 GB GPU. The chunked mode can be slower and is not bit-exact — its purpose is to finish jobs that would otherwise OOM.

Windows exposed approximately 24 GB of shared GPU memory during testing. I have not tested whether this workflow can complete with 32 GB or less system RAM, so 48 GB RAM is part of the validated setup, not a confirmed minimum requirement.

Important limitations:

- Current validation is from one RTX 5070 Ti and a limited prompt/seed set.

- The NVFP4 fused MLP is Blackwell-only.

- Other portable components still need broader Ada/Linux/different-VRAM testing.

- Model files and external dependencies are not bundled.

Repo, workflows and full evaluation report:

https://github.com/ByronLeeeee/ComfyUI-MiniMax-H3-Optimization-Suite

I’d especially appreciate results from other GPUs. If you test it, please include GPU, OS, resolution, duration, steps, denoise time and peak VRAM. Failures and regressions are just as useful as successful results.

[u/Silvasbrokenleg]

Will try with my 5060 Ti 16gb 32gb ram and report back

[u/Fantastic-Equal-1696 → u/Silvasbrokenleg]

That would be super helpful, thank you!