NimbleMoE: Collaboration-Aware Expert Merging with Sparse Compensation for Efficient Mixture-of-Experts LLMs

Zhiyuan Ning, Xiaoran Liu, Ruge Xu, Xinfei Guo, Ziwei He, Xipeng Qiu


Abstract
Mixture-of-Experts (MoE) Transformers improve scaling efficiency by activating only a subset of experts per token, but deployed inference remains constrained by memory capacity and bandwidth. Existing expert compression methods face a quality–memory–latency trilemma: pruning or fully merging degrades model quality, while partial merging increases per-token activated parameters and hurt latency. We propose NimbleMoE, a training-free, collaboration-aware partial expert merging framework that reduces both model size and activated-parameter cost. NimbleMoE clusters experts by routing co-activation so co-activated experts share a low-rank subspace. To compensate for the capacity lost, NimbleMoE adds hardware-efficient Monarch residuals, with an alignment-aware choice between latent-space and output-space compensation. Across multiple MoE backbones, NimbleMoE preserves model quality under 20–25% total-parameter compression and outperforms prior pruning and merging baselines, while delivering up to 1.89× MoE-MLP kernel speedup in bandwidth-bound settings, 1.31× end-to-end TPOT speedup, and 2.81× expert-parallel MoE-kernel speedup.
Anthology ID:
2026.emnlp-main.2036
Volume:
Proceedings of the 2026 Conference on Empirical Methods in Natural Language Processing
Month:
October
Year:
2026
Address:
Budapest, Hungary
Editors:
Hung-Yi Lee, Sunipa Dev, Jessy Li, Desmond Elliott
Venue:
EMNLP
SIG:
SIGDAT
Publisher:
Association for Computational Linguistics
Note:
Pages:
46390–46408
Language:
URL:
https://aclanthology.org/2026.emnlp-main.2036/
DOI:
Bibkey:
Cite (ACL):
Zhiyuan Ning, Xiaoran Liu, Ruge Xu, Xinfei Guo, Ziwei He, and Xipeng Qiu. 2026. NimbleMoE: Collaboration-Aware Expert Merging with Sparse Compensation for Efficient Mixture-of-Experts LLMs. In Proceedings of the 2026 Conference on Empirical Methods in Natural Language Processing, pages 46390–46408, Budapest, Hungary. Association for Computational Linguistics.
Cite (Informal):
NimbleMoE: Collaboration-Aware Expert Merging with Sparse Compensation for Efficient Mixture-of-Experts LLMs (Ning et al., EMNLP 2026)
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PDF:
https://aclanthology.org/2026.emnlp-main.2036.pdf