FastH3 + USDU doubles video upscale speed on RTX 3090: 48m vs 96m, full workflow released
inazma44 · reddit · 2026-09-07
After days of testing with an AI agent, the author combined FastH3 (MiniMax H3) with Ultimate SD Upscale for restoring low-quality AI generations, and published a reproducible workflow.
Benchmarks (15s source, 2752×1536, 2 steps, denoise 0.20, RTX 3090 24GB):
- H3 + 4-step Turbo LoRA / USDU: 96m 37s
- FastH3 / USDU: 48m 40s (2× faster)
- FastH3 / MMH3 single-node upscale: 47m 36s
Verdict: FastH3 + USDU wins — the single-node path saves 1 minute but introduces more distortion; both final paths finish with pixel-domain ESRGAN upscaling.
Caveats: single successful runs with different cache states, not a strict model-only benchmark; FastH3 USDU hit two OOMs requiring a memory-estimation override. A 5-second clip also ran on an RTX 4070 Ti SUPER (16GB VRAM).
The full workflow and Windows installer (English instructions, 41GB model links) are on GitHub; read the installer notes — it updates Kitchen and applies fingerprint-guarded H3 core patches.
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