Spectrum Acceleration - SGLang Documentation

Spectrum forecasts DiT features and skips selected denoising steps. It is an approximation: validate visual or video quality and latency on the exact model, shape, hardware, and sampling settings you plan to deploy.

Quick start

sglang generate \
  --model-path Wan-AI/Wan2.1-T2V-1.3B-Diffusers \
  --prompt "A paper boat floating through a misty mountain lake" \
  --enable-spectrum \
  --save-output

Scope and constraints

Available only on native FLUX.1, Wan, HunyuanVideo, and SD3 implementation paths. It is not a --backend diffusers feature and does not currently cover FLUX.2.
The request control is available through sglang generate and Python sampling parameters. It is not a sglang serve or OpenAI-server request option yet.
Spectrum and --enable-teacache are mutually exclusive.
Start with the defaults. --debug adds shadow-prediction validation work, so its latency is not representative of normal Spectrum execution.

Advanced controls

Use --enable-spectrum explicitly. Providing any Spectrum override also enables it, but that implicit behavior is intended for scripts rather than new commands.

Flag	Default	Purpose
`--spectrum-window-size`	`2.0`	Initial step-skipping window
`--spectrum-flex-window`	`0.75`	Window growth after a real forward
`--spectrum-warmup-steps`	`5`	Initial exact DiT forwards
`--spectrum-m`	`4`	Chebyshev basis count
`--spectrum-lam`	`0.1`	Ridge regularization
`--spectrum-tau-num-steps`	`50`	Chebyshev time horizon
`--history-size`	`100`	Recent feature-history capacity
`--taylor-order`	`1`	Local predictor order (`1`, `2`, or `3`)
`--w`	`1.0`	Chebyshev/Taylor blend weight

These controls trade speed against output fidelity. Change one control at a time and retain a lossless baseline for comparison.

​Quick start

​Scope and constraints

​Advanced controls

Quick start

Scope and constraints

Advanced controls