FastH3-Live hits 22fps: acceleration node benchmarks and the --vram-headroom trick

spartong945 · reddit · 2026-09-11

FastH3-Live v1.2.0 lifts live video generation from 18 to 22fps (91.6% of 24fps), with full benchmarks.

Acceleration nodes (448x448×362 frames, 3 runs): Sol + Spectrum was fastest (−23.8% sampler time, 20.96fps) but ranked last on picture quality; author chose sage + Spectrum (−18.1%, 20.18fps).

Text encoder: swapping int8convrot (1.67s) for qwen3vl32bminimaxh3nvfp4awq (0.7s) saves 1s per clip.

fused-turbo vs own quantized weights: identical size (21GB) and speed, but fused-turbo merges Mystic v2.0 motion smoothing (better picture) and handles both fl2va and ref2va in one file — a real win for live streaming with reference images.

Key gotcha: --vram-headroom 3 is required to stop ComfyUI thrashing weights — keeping 3GB VRAM free lets weights load in whole batches; without it PCIe reads spike to 9-13GB/s as weights get evicted and reloaded repeatedly. Ships a borderless player and 400 new scenes.

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