On the Overscaling Curse of Parallel Thinking: System Efficacy Contradicts Sample Efficiency

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Autori principali: Wang, Yiming, Zhang, Zhuosheng, Wang, Rui
Natura: Preprint
Pubblicazione: 2026
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author Wang, Yiming
Zhang, Zhuosheng
Wang, Rui
author_facet Wang, Yiming
Zhang, Zhuosheng
Wang, Rui
contents Parallel thinking improves LLM reasoning through multi-path sampling and aggregation. In standard evaluations, due to a lack of sample-specific priors, all samples share a global budget chosen to maximize dataset accuracy. However, many samples reach their best accuracy with much smaller budgets, causing low budget utilization. This contradiction between system efficacy and sample efficiency constitutes the Overscaling Curse. In this paper, we first provide a formal analysis of the overscaling curse and quantify its prevalence and severity in real-world systems. To break it, we propose Latent Budget Predictor (LanBo), which probes model latent representations to predict sample-specific optimal budgets. LanBo significantly improves budget utilization while maintaining dataset accuracy. We further integrate LanBo into the full decoding pipeline, inspiring Pre-decoding Budget Adaptation (PreAda), a paradigm that allocates budgets before decoding to preserve decoding-time parallelization. LanBo substantially improves hardware-aware efficiency in latency and memory, demonstrating both its practical value and the promise of LanBo for efficient parallel decoding.
format Preprint
id arxiv_https___arxiv_org_abs_2601_21619
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle On the Overscaling Curse of Parallel Thinking: System Efficacy Contradicts Sample Efficiency
Wang, Yiming
Zhang, Zhuosheng
Wang, Rui
Machine Learning
Artificial Intelligence
Computation and Language
Parallel thinking improves LLM reasoning through multi-path sampling and aggregation. In standard evaluations, due to a lack of sample-specific priors, all samples share a global budget chosen to maximize dataset accuracy. However, many samples reach their best accuracy with much smaller budgets, causing low budget utilization. This contradiction between system efficacy and sample efficiency constitutes the Overscaling Curse. In this paper, we first provide a formal analysis of the overscaling curse and quantify its prevalence and severity in real-world systems. To break it, we propose Latent Budget Predictor (LanBo), which probes model latent representations to predict sample-specific optimal budgets. LanBo significantly improves budget utilization while maintaining dataset accuracy. We further integrate LanBo into the full decoding pipeline, inspiring Pre-decoding Budget Adaptation (PreAda), a paradigm that allocates budgets before decoding to preserve decoding-time parallelization. LanBo substantially improves hardware-aware efficiency in latency and memory, demonstrating both its practical value and the promise of LanBo for efficient parallel decoding.
title On the Overscaling Curse of Parallel Thinking: System Efficacy Contradicts Sample Efficiency
topic Machine Learning
Artificial Intelligence
Computation and Language
url https://arxiv.org/abs/2601.21619