Rethinking LoRA Memory Through the Lens of KV Cache Compression

Chunsheng Zuo, Liaoyaqi Wang, William Jurayj, William Fleshman, Benjamin Van Durme


Abstract
Parametric retrieval augmentation encodes document information into lightweight, document-specific modules such as LoRA adapters, reducing the need to include all evidence as input context. However, it remains unclear how this parameter-side memory interacts with context-side memory stored in the KV cache. We study this interaction in document-level question answering by progressively evicting document key-value states and measuring when a document LoRA contributes beyond the retained context. We find that document LoRA adds little when the KV cache is largely intact, but becomes increasingly useful under aggressive compression, recovering 13–21 ROUGE-L points when no document context remains. The gain is largest when the base model encodes the document, and the adapter is applied only during answer generation, suggesting that LoRA serves as decoding-time parametric memory rather than as a document encoder. Finally, QA-style supervision produces substantially stronger adapters than raw-context, continuation, or context-plus-QA objectives. These results position document LoRA as a complementary memory channel whose value emerges precisely when context-side evidence is scarce.
Anthology ID:
2026.emnlp-main.733
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:
17013–17030
Language:
URL:
https://aclanthology.org/2026.emnlp-main.733/
DOI:
Bibkey:
Cite (ACL):
Chunsheng Zuo, Liaoyaqi Wang, William Jurayj, William Fleshman, and Benjamin Van Durme. 2026. Rethinking LoRA Memory Through the Lens of KV Cache Compression. In Proceedings of the 2026 Conference on Empirical Methods in Natural Language Processing, pages 17013–17030, Budapest, Hungary. Association for Computational Linguistics.
Cite (Informal):
Rethinking LoRA Memory Through the Lens of KV Cache Compression (Zuo et al., EMNLP 2026)
Copy Citation:
PDF:
https://aclanthology.org/2026.emnlp-main.733.pdf