FlashMap Drafts 16 Dependent Tokens at Once, Hitting 6.1x Faster Decoding
A flow-map drafter conditions on hidden states to generate entire token blocks in one shot, hitting 6.1x lossless speedups on Qwen3-8B.
- FlashMap is a new speculative decoding drafter based on continuous flow maps.
- Generates an entire token block in one pass while modeling inter-token dependencies.
- Delivers up to 6.1x lossless speedup on Qwen3-8B, beating DFlash on every benchmark.
- Conditions the flow map on target model hidden states for better acceptance rates.
- Open-source code with SGLang and vLLM integration available.
- Pretrained drafters for Qwen3-8B and Qwen3-4B released on Hugging Face.
The FlashMap paper introduces a speculative-decoding drafter that generates an entire token block with a continuous flow map. The method retains parallel block generation while modeling dependencies among tokens within the block.
On Qwen3-8B, the authors report up to 6.1x lossless acceleration over ordinary target-model decoding and a 7% higher average speedup than a matched DFlash baseline.
Why drafting still costs time
Speculative decoding pairs an accurate target model with a smaller drafter to reduce the number of sequential target-model calls. Each decoding cycle follows four steps:
- The drafter proposes a block of candidate tokens.
- The target model scores the full block in parallel.
- The verifier accepts the longest valid prefix.
- After a rejection, decoding resumes from a target-model token.
In this context, “lossless” means the verifier preserves the target model’s output distribution under the same sampling settings. Greedy decoding produces the same result as ordinary target-model decoding when the verifier is implemented correctly.
| Drafter | Block generation | Token dependencies | Primary cost |
|---|---|---|---|
| Autoregressive, including EAGLE-style models | Sequential | Each token sees earlier draft tokens | Proposal latency grows with block length |
| DFlash-style diffusion | Parallel | Positions are predicted independently under the paper’s formulation | Acceptance declines at later block positions |
| FlashMap | Parallel flow map | The block is modeled jointly |
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