PerfCoder: Large Language Models for Interpretable Code Performance Optimization

Fuente: arXiv
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Main Authors: Yang, Jiuding, Lu, Shengyao, Liu, Hongxuan, Bagi, Shayan Shirahmad Gale, Fazel, Zahra, Czajkowski, Tomasz, Niu, Di
Format: Preprint
Published: 2025
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author Yang, Jiuding
Lu, Shengyao
Liu, Hongxuan
Bagi, Shayan Shirahmad Gale
Fazel, Zahra
Czajkowski, Tomasz
Niu, Di
author_facet Yang, Jiuding
Lu, Shengyao
Liu, Hongxuan
Bagi, Shayan Shirahmad Gale
Fazel, Zahra
Czajkowski, Tomasz
Niu, Di
contents Large language models (LLMs) have achieved remarkable progress in automatic code generation, yet their ability to produce high-performance code remains limited--a critical requirement in real-world software systems. We argue that current LLMs struggle not only due to data scarcity but, more importantly, because they lack supervision that guides interpretable and effective performance improvements. In this work, we introduce PerfCoder, a family of LLMs specifically designed to generate performance-enhanced code from source code via interpretable, customized optimizations. PerfCoder is fine-tuned on a curated collection of real-world optimization trajectories with human-readable annotations, and preference-aligned by reinforcement fine-tuning using runtime measurements, enabling it to propose input-specific improvement strategies and apply them directly without relying on iterative refinement. On the PIE code performance benchmark, PerfCoder surpasses all existing models in both runtime speedup and effective optimization rate, demonstrating that performance optimization cannot be achieved by scale alone but requires optimization stratetgy awareness. In addition, PerfCoder can generate interpretable feedback about the source code, which, when provided as input to a larger LLM in a planner-and-optimizer cooperative workflow, can further improve outcomes. Specifically, we elevate the performance of 32B models and GPT-5 to new levels on code optimization, substantially surpassing their original performance.
format Preprint
id arxiv_https___arxiv_org_abs_2512_14018
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle PerfCoder: Large Language Models for Interpretable Code Performance Optimization
Yang, Jiuding
Lu, Shengyao
Liu, Hongxuan
Bagi, Shayan Shirahmad Gale
Fazel, Zahra
Czajkowski, Tomasz
Niu, Di
Software Engineering
Artificial Intelligence
Large language models (LLMs) have achieved remarkable progress in automatic code generation, yet their ability to produce high-performance code remains limited--a critical requirement in real-world software systems. We argue that current LLMs struggle not only due to data scarcity but, more importantly, because they lack supervision that guides interpretable and effective performance improvements. In this work, we introduce PerfCoder, a family of LLMs specifically designed to generate performance-enhanced code from source code via interpretable, customized optimizations. PerfCoder is fine-tuned on a curated collection of real-world optimization trajectories with human-readable annotations, and preference-aligned by reinforcement fine-tuning using runtime measurements, enabling it to propose input-specific improvement strategies and apply them directly without relying on iterative refinement. On the PIE code performance benchmark, PerfCoder surpasses all existing models in both runtime speedup and effective optimization rate, demonstrating that performance optimization cannot be achieved by scale alone but requires optimization stratetgy awareness. In addition, PerfCoder can generate interpretable feedback about the source code, which, when provided as input to a larger LLM in a planner-and-optimizer cooperative workflow, can further improve outcomes. Specifically, we elevate the performance of 32B models and GPT-5 to new levels on code optimization, substantially surpassing their original performance.
title PerfCoder: Large Language Models for Interpretable Code Performance Optimization
topic Software Engineering
Artificial Intelligence
url https://arxiv.org/abs/2512.14018