Accelerate Speculative Decoding with Sparse Computation in Verification

Jikai Wang, Jianchao Tan, Yuxuan Hu, Jiayu Qin, Yerui Sun, Yuchen Xie, Xunliang Cai, Juntao Li, Min Zhang


Abstract
Speculative decoding accelerates autoregressive language model inference by verifying multiple draft tokens in parallel. However, the verification stage often becomes the dominant computational bottleneck, especially for long-context inputs and mixture-of-experts (MoE) models. Existing sparsification methods are designed primarily for token-by-token autoregressive decoding to remove substantial computational redundancy in LLMs. This work systematically adopts different sparse methods on the verification stage of the speculative decoding and identifies structured redundancy across multiple dimensions. Based on these observations, we propose a sparse verification framework that jointly sparsifies attention, FFN, and MoE components during the verification stage to reduce the dominant computation cost. The framework further incorporates an inter-draft token and inter-layer retrieval reuse strategy to further reduce redundant computation without introducing additional training. Extensive experiments across summarization, question answering, and mathematical reasoning datasets demonstrate that the proposed methods achieve favorable efficiency-accuracy trade-offs and can be translated into practical latency reduction with optimized sparse kernels.
Anthology ID:
2026.findings-emnlp.2231
Volume:
Findings of the Association for Computational Linguistics: EMNLP 2026
Month:
October
Year:
2026
Address:
Budapest, Hungary
Editors:
Hung-Yi Lee, Sunipa Dev, Jessy Li, Desmond Elliott
Venue:
Findings
SIG:
SIGDAT
Publisher:
Association for Computational Linguistics
Note:
Pages:
47762–47775
Language:
URL:
https://aclanthology.org/2026.findings-emnlp.2231/
DOI:
Bibkey:
Cite (ACL):
Jikai Wang, Jianchao Tan, Yuxuan Hu, Jiayu Qin, Yerui Sun, Yuchen Xie, Xunliang Cai, Juntao Li, and Min Zhang. 2026. Accelerate Speculative Decoding with Sparse Computation in Verification. In Findings of the Association for Computational Linguistics: EMNLP 2026, pages 47762–47775, Budapest, Hungary. Association for Computational Linguistics.
Cite (Informal):
Accelerate Speculative Decoding with Sparse Computation in Verification (Wang et al., Findings 2026)
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PDF:
https://aclanthology.org/2026.findings-emnlp.2231.pdf