Understanding LLM Performance Degradation in Multi-Instance Processing: The Roles of Instance Count and Context Length

Fuente: arXiv
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Autores principales: Chen, Jingxuan, Pilehvar, Mohammad Taher, Camacho-Collados, Jose
Formato: Preprint
Publicado: 2026
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author Chen, Jingxuan
Pilehvar, Mohammad Taher
Camacho-Collados, Jose
author_facet Chen, Jingxuan
Pilehvar, Mohammad Taher
Camacho-Collados, Jose
contents Users often rely on Large Language Models (LLMs) for processing multiple documents or performing analysis over a number of instances. For example, analysing the overall sentiment of a number of movie reviews requires an LLM to process the sentiment of each review individually in order to provide a final aggregated answer. While LLM performance on such individual tasks is generally high, there has been little research on how LLMs perform when dealing with multi-instance inputs. In this paper, we perform a comprehensive evaluation of the multi-instance processing (MIP) ability of LLMs for tasks in which they excel individually. The results show that all LLMs follow a pattern of slight performance degradation for small numbers of instances (approximately 20-100), followed by a performance collapse on larger instance counts. Crucially, our analysis shows that while context length is associated with this degradation, the number of instances has a stronger effect on the final results. This finding suggests that when optimising LLM performance for MIP, attention should be paid to both context length and, in particular, instance count.
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id arxiv_https___arxiv_org_abs_2603_22608
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Understanding LLM Performance Degradation in Multi-Instance Processing: The Roles of Instance Count and Context Length
Chen, Jingxuan
Pilehvar, Mohammad Taher
Camacho-Collados, Jose
Artificial Intelligence
Computation and Language
Users often rely on Large Language Models (LLMs) for processing multiple documents or performing analysis over a number of instances. For example, analysing the overall sentiment of a number of movie reviews requires an LLM to process the sentiment of each review individually in order to provide a final aggregated answer. While LLM performance on such individual tasks is generally high, there has been little research on how LLMs perform when dealing with multi-instance inputs. In this paper, we perform a comprehensive evaluation of the multi-instance processing (MIP) ability of LLMs for tasks in which they excel individually. The results show that all LLMs follow a pattern of slight performance degradation for small numbers of instances (approximately 20-100), followed by a performance collapse on larger instance counts. Crucially, our analysis shows that while context length is associated with this degradation, the number of instances has a stronger effect on the final results. This finding suggests that when optimising LLM performance for MIP, attention should be paid to both context length and, in particular, instance count.
title Understanding LLM Performance Degradation in Multi-Instance Processing: The Roles of Instance Count and Context Length
topic Artificial Intelligence
Computation and Language
url https://arxiv.org/abs/2603.22608