arXivPaperNeeds Review

Latent Sparse Attention: Towards Subquadratic Ultra-Long Context Attention

Latent Sparse Attention uses learned clusters to avoid scoring every key in ultra-long contexts. The reported gains are large at 10M tokens, but apply to one attention layer in the evaluated model.

arXiv · Oct 30, 2026

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Source Summary

Latent Sparse Attention (LSA) groups keys hierarchically in a learned latent space, letting queries score clusters instead of every key. On GLM-5.3-FLASH (QWEN-3.8-27B) at **10M tokens**, Distilled-LSA reports **22.7×** prefill and **4.6×** decode speedups over the model's original sparse attention.

Practical Implication

For agent runs that accumulate very long histories, this points to attention indexing as a possible bottleneck and optimization target. The paper offers a distilled variant for pretrained models and a native variant trained on next-token loss.

Agent-Ready Context

Latent Sparse Attention (LSA) groups keys hierarchically in a learned latent space, letting queries score clusters instead of every key. On GLM-5.3-FLASH (QWEN-3.8-27B) at **10M tokens**, Distilled-LSA reports **22.7×** prefill and **4.6×** decode speedups over the model's original sparse attention.

For agent runs that accumulate very long histories, this points to attention indexing as a possible bottleneck and optimization target. The paper offers a distilled variant for pretrained models and a native variant trained on next-token loss.

The speedups are for one attention layer, and the baselines differ: the figures in parentheses compare against full attention. The material says accuracy stayed similar across tasks for Distilled-LSA; Native-LSA's full-attention accuracy match and 1.6× training speedup are reported at 128k tokens.

Context Map

modelresearch

Uncertainty

The speedups are for one attention layer, and the baselines differ: the figures in parentheses compare against full attention. The material says accuracy stayed similar across tasks for Distilled-LSA; Native-LSA's full-attention accuracy match and 1.6× training speedup are reported at 128k tokens.