Modular Representation Compression: Adapting LLMs for Efficient and Effective Recommendations

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Hauptverfasser: Xi, Yunjia, Zhu, Menghui, Lin, Jianghao, Chen, Bo, Tang, Ruiming, Yu, Yong, Zhang, Weinan
Format: Preprint
Veröffentlicht: 2026
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author Xi, Yunjia
Zhu, Menghui
Lin, Jianghao
Chen, Bo
Tang, Ruiming
Yu, Yong
Zhang, Weinan
author_facet Xi, Yunjia
Zhu, Menghui
Lin, Jianghao
Chen, Bo
Tang, Ruiming
Yu, Yong
Zhang, Weinan
contents Recently, large language models (LLMs) have advanced recommendation systems (RSs), and recent works have begun to explore how to integrate LLMs into industrial RSs. While most approaches deploy LLMs offline to generate and pre-cache augmented representations for RSs, high-dimensional representations from LLMs introduce substantial storage and computational costs. Thus, it is crucial to compress LLM representations effectively. However, we identify a counterintuitive phenomenon during representation compression: Mid-layer Representation Advantage (MRA), where representations from middle layers of LLMs outperform those from final layers in recommendation tasks. This degraded final layer renders existing compression methods, which typically compress on the final layer, suboptimal. We interpret this based on modularity theory that LLMs develop spontaneous internal functional modularity and force the final layer to specialize in the proxy training task. Thus, we propose \underline{M}odul\underline{a}r \underline{R}epresentation \underline{C}ompression (MARC) to explicitly control the modularity of LLMs. First, Modular Adjustment explicitly introduces compression and task adaptation modules, enabling the LLM to operate strictly as a representation-learning module. Next, to ground each module to its specific task, Modular Task Decoupling uses information constraints and different network structures to decouple tasks. Extensive experiments validate that MARC addresses MRA and produces efficient representations. Notably, MARC achieved a 2.82% eCPM lift in an online A/B test within a large-scale commercial search advertising scenario.
format Preprint
id arxiv_https___arxiv_org_abs_2604_18146
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Modular Representation Compression: Adapting LLMs for Efficient and Effective Recommendations
Xi, Yunjia
Zhu, Menghui
Lin, Jianghao
Chen, Bo
Tang, Ruiming
Yu, Yong
Zhang, Weinan
Information Retrieval
Artificial Intelligence
Computation and Language
Recently, large language models (LLMs) have advanced recommendation systems (RSs), and recent works have begun to explore how to integrate LLMs into industrial RSs. While most approaches deploy LLMs offline to generate and pre-cache augmented representations for RSs, high-dimensional representations from LLMs introduce substantial storage and computational costs. Thus, it is crucial to compress LLM representations effectively. However, we identify a counterintuitive phenomenon during representation compression: Mid-layer Representation Advantage (MRA), where representations from middle layers of LLMs outperform those from final layers in recommendation tasks. This degraded final layer renders existing compression methods, which typically compress on the final layer, suboptimal. We interpret this based on modularity theory that LLMs develop spontaneous internal functional modularity and force the final layer to specialize in the proxy training task. Thus, we propose \underline{M}odul\underline{a}r \underline{R}epresentation \underline{C}ompression (MARC) to explicitly control the modularity of LLMs. First, Modular Adjustment explicitly introduces compression and task adaptation modules, enabling the LLM to operate strictly as a representation-learning module. Next, to ground each module to its specific task, Modular Task Decoupling uses information constraints and different network structures to decouple tasks. Extensive experiments validate that MARC addresses MRA and produces efficient representations. Notably, MARC achieved a 2.82% eCPM lift in an online A/B test within a large-scale commercial search advertising scenario.
title Modular Representation Compression: Adapting LLMs for Efficient and Effective Recommendations
topic Information Retrieval
Artificial Intelligence
Computation and Language
url https://arxiv.org/abs/2604.18146