WindowQuant: Mixed-Precision KV Cache Quantization based on Window-Level Similarity for VLMs Inference Optimization

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Main Authors: Tao, Wei, Qu, Xiaoyang, Wang, Peiqiang, Li, Guokuan, Wan, Jiguang, Lu, Kai, Wang, Jianzong
Format: Preprint
Published: 2026
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author Tao, Wei
Qu, Xiaoyang
Wang, Peiqiang
Li, Guokuan
Wan, Jiguang
Lu, Kai
Wang, Jianzong
author_facet Tao, Wei
Qu, Xiaoyang
Wang, Peiqiang
Li, Guokuan
Wan, Jiguang
Lu, Kai
Wang, Jianzong
contents Recently, video language models (VLMs) have been applied in various fields. However, the visual token sequence of the VLM is too long, which may cause intolerant inference latency and GPU memory usage. Existing methods propose mixed-precision quantization to the key-value (KV) cache in VLMs based on token granularity, which is time-consuming in the search process and hardware inefficient during computation. This paper introduces a novel approach called WindowQuant, which employs window-adaptive mixed-precision quantization to optimize the KV cache. WindowQuant consists of two modules: window-level quantization search and window-level KV cache computation. Window-level quantization search quickly determines the optimal bit-width configuration of the KV cache windows based on the similarity scores between the corresponding visual token windows and the text prompt, maintaining the model accuracy. Furthermore, window-level KV cache computation reorders the KV cache windows before quantization, avoiding the hardware inefficiency caused by mixed-precision quantization in inference computation. Extensive experiments demonstrate that WindowQuant outperforms state-of-the-art VLM models and KV cache quantization methods on various datasets.
format Preprint
id arxiv_https___arxiv_org_abs_2605_02262
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle WindowQuant: Mixed-Precision KV Cache Quantization based on Window-Level Similarity for VLMs Inference Optimization
Tao, Wei
Qu, Xiaoyang
Wang, Peiqiang
Li, Guokuan
Wan, Jiguang
Lu, Kai
Wang, Jianzong
Computer Vision and Pattern Recognition
Computation and Language
Recently, video language models (VLMs) have been applied in various fields. However, the visual token sequence of the VLM is too long, which may cause intolerant inference latency and GPU memory usage. Existing methods propose mixed-precision quantization to the key-value (KV) cache in VLMs based on token granularity, which is time-consuming in the search process and hardware inefficient during computation. This paper introduces a novel approach called WindowQuant, which employs window-adaptive mixed-precision quantization to optimize the KV cache. WindowQuant consists of two modules: window-level quantization search and window-level KV cache computation. Window-level quantization search quickly determines the optimal bit-width configuration of the KV cache windows based on the similarity scores between the corresponding visual token windows and the text prompt, maintaining the model accuracy. Furthermore, window-level KV cache computation reorders the KV cache windows before quantization, avoiding the hardware inefficiency caused by mixed-precision quantization in inference computation. Extensive experiments demonstrate that WindowQuant outperforms state-of-the-art VLM models and KV cache quantization methods on various datasets.
title WindowQuant: Mixed-Precision KV Cache Quantization based on Window-Level Similarity for VLMs Inference Optimization
topic Computer Vision and Pattern Recognition
Computation and Language
url https://arxiv.org/abs/2605.02262