Rethinking Token Reduction for Large Vision-Language Models
Authors: Yi Wang, Haofei Zhang, Qihan Huang, Anda Cao, Gongfan Fang, Wei Wang, Xuan Jin, Jie Song, Mingli Song, Xinchao Wang
Organizations: College of Computer Science and Technology, Zhejiang University · State Key Laboratory of Blockchain and Data Security, Zhejiang University · Hangzhou High-Tech Zone (Binjiang) Institute of Blockchain and Data Security · National University of Singapore · Alibaba Group · School of Software Technology, Zhejiang University
Large Vision-Language Models (LVLMs) excel in visual understanding and reasoning, but the excessive visual tokens lead to high inference costs. Although recent token reduction methods mitigate this issue, they mainly target single-turn Visual Question Answering (VQA), leaving the more practical multi-turn VQA (MT-VQA) scenario largely unexplored. MT-VQA introduces additional challenges, as subsequent questions are unknown beforehand and may refer to arbitrary image regions, making existing reduction strategies ineffective. Specifically, current approaches fall into two categories: prompt-dependent methods, which bias toward the initial text prompt and discard information useful for subsequent turns; prompt-agnostic ones, which, though technically applicable to multi-turn settings, rely on heuristic reduction metrics such as attention scores, leading to suboptimal performance. In this paper, we propose a learning-based prompt-agnostic method, termed MetaCompress, overcoming the limitations of heuristic designs. We begin by formulating token reduction as a learnable compression mapping, unifying existing formats such as pruning and merging into a single learning objective. Upon this formulation, we introduce a data-efficient training paradigm capable of learning optimal compression mappings with limited computational costs. Extensive experiments on MT-VQA benchmarks and across multiple LVLM architectures demonstrate that MetaCompress achieves superior efficiency-accuracy trade-offs while maintaining strong generalization across dialogue turns. Our code is available at https://github.com/MArSha1147/MetaCompress.
Figures & tables
Figure 1: (a) Overall pipeline of the compression projection training process. (b) Attention distribution over the [ CLS ] token for retained and all visual tokens. The image tokens are extracted from the last layer of the vision tower of LLaVA-1.5-13b running on VQA-v2 dataset. (c) Attention distribution over the prompt tokens for retained and all visual tokens. The attention scores are averaged to prompt tokens extracted from the first layer of the LLM decoder.
Figure 2: Illustration of our proposed MetaCompress, where module Pmeta generate the compression projection P solely according to the image sequence XIMG .
Model
Method
MT-VQA-v2
MT-GQA
ConvBench
Acc1
Acc2
Acc3
Avg
Acc1
Acc2
Acc3
Avg
S1
S2
S3
Avg
LLaVA-1.5-7b
Base
76.72
77.51
77.30
77.18
61.76
64.07
65.35
63.73
4.33
5.72
5.55
5.20
Random
66.36
66.94
66.68
66.66
54.60
57.07
59.31
56.99
3.73
3.99
4.08
3.93
Sample
67.11
67.52
67.63
67.42
55.06
57.89
59.74
57.56
3.64
4.85
3.81
4.10
FastV
45.98
48.56
49.65
48.06
40.98
46.71
49.30
45.66
1.56
1.39
3.12
2.02
PruMerge
69.03
69.93
69.73
69.56
55.26
57.23
60.13
57.54
4.51
3.47
3.47
3.82
Table 1: The comparison of visual token reduction methods on three MT-VQA benchmarks with the reduction rate of 90%. The best and the second-best results are highlighted in bold and underline, respectively.
Figure 3: Comparison of average accuracy on MT-GQA with reduction rate from 50% to 95%.
Model
Setting
TTFT
E2ET
Mem.
TFLOPs
LLaVA-1.5-7b
Base
232 ( ± 5.8)
676 ( ± 8.0)
26.9
71.4
Random
98.2 ( ± 5.7)
487 ( ± 4.6)
26.2
13.3
Sample
96.9 ( ± 5.8)
482 ( ± 4.9)
26.2
13.3
FastV
102 ( ± 4.52)
528 ( ± 6.0)
26.3
13.5
PruMerge
107 ( ± 5.23)
509 ( ± 4.5)
26.2
13.3
Ours
97.8 ( ± 5.41)
480 ( ± 5.1)
26.1
13.3
Table 2: Efficiency comparison of different token reduction methods. The time to first token (TTFT, ms), end-to-end generation time (E2ET, ms), GPU memory usage (Mem. GB), and TFLOPs are reported on MT-GQA dataset with a reduction rate of 90%.
Settings
MT-GQA
Lpred
Lentropy
Lcollapse
Lcollapse + Grad Clip
Avg
✓
✗
✗
✗
61.98
✓
✓
✗
✗
62.42
✓
✗
✓
✗
56.34
✓
✗
✗
✓
62.13
✓
✓
✗
✓
62.70
Table 3: Ablation study of training MetaCompress for LLaVA-NeXT-7b using different loss terms on MT-GQA. Gradient clipping is only applied for the ‘ Lcollapse + Grad Clip ’ setting.
Figure 4: Sensitivity analysis in training MetaCompress for LLaVA-NeXT-7b with different weights αentropy and αcollapse on MT-GQA.
Figure 5: (a) Token importance distribution. (b) Attention distribution over prompt tokens. Image tokens are extracted from the last layer of the vision tower of LLaVA-NeXT-7b on VQA-v2 dataset.
Model
Method
MT-VQA-v2
MT-GQA
ConvBench
Acc1
Acc2
Acc3
Avg
Acc1
Acc2
Acc3
Avg
S1
S2
S3
Avg
LLaVA-1.5-7b
Base
76.72
77.51
77.30
77.18
61.76
64.07
65.35
63.73
4.33
5.72
5.55
5.20
Random
72.72
73.57
73.11
73.13
57.79
61.07
63.09
60.65
4.17
4.73
5.51
4.80
Sample
72.96
73.71
73.33
73.33
58.48
61.12
62.30
60.63
4.16
5.03
3.81
4.33
FastV
69.30
69.57
69.41
69.43
54.79
57.65
60.03
57.49
3.99
5.03
3.47
4.16
PruMerge
72.79
73.90
73.42
73.37
57.89
59.54
61.81
59.75
3.64
4.68
4.68
4.33
Table 4: The comparison of visual token reduction methods on three MT-VQA benchmarks with the reduction rate of 70%. The best and the second-best results are highlighted in bold and underline, respectively.
Setting
MT-GQA
Acc1
Acc2
Acc3
Avg
Base
61.76
64.07
65.35
63.73
Sample
54.60
57.07
59.31
56.99
Spatial
51.05
54.62
56.24
53.97
ToMe
53.64
56.91
57.62
56.06
VisionZip
55.08
57.82
59.89
57.60
Table 5: Comparison results of different token merging methods for LLaVA-1.5-7b.
Lpred
Lentropy
Lcollapse
Lcollapse + Grad Clip
LLaVA-1.5-7b
LLaVA-NeXT-7b
XComposer-2.5-7b
✓
✗
✗
✗
56.63
61.98
56.77
✓
✓
✗
✗
57.99
62.42
58.01
✓
✗
✓
✗
52.26
56.34
52.53
✓
✗
✗
✓
57.57
62.13
58.24
✓
✓
✗
✓
58.43
62.70
58.68
Table 6: Additional ablation study of training MetaCompress for various LVLMs using different loss terms on MT-GQA. Gradient clipping is only applied for the ‘ Lcollapse + Grad Clip ’ setting.
Settings
LLaVA-1.5-7b
LLaVA-1.5-13b
LLaVA-NeXT-7b
LLaVA-NeXT-13b
XComposer-2.5-7b
MT-VQA-v2
70.65
72.94
75.18
75.26
75.76
MT-GQA → MT-VQA-v2
69.06
71.89
73.61
73.25
74.41
MT-GQA
58.43
59.48
62.70
63.12
58.68
MT-VQA-v2 → MT-GQA
57.45
58.78
61.43
62.60
58.06
Table 7: Transfer validation experiments. Average accuracy is reported for cross-dataset transfer between MT-VQA-V2 and MT-GQA, all under a 90% token reduction rate.
Metrics
Base
Random
Sample
FastV
Ours
Acc1
44.3
26.8
25.5
26.2
28.5
Acc2
46.7
25.3
26.4
27.3
27.3
Acc3
48.2
30.7
31.3
31.6
34.6
Avg
46.4
27.6
27.7
28.4
30.1
Table 8: Transfer results on MT-Video-MME. Average accuracy is reported across different methods.
Figure 6: Visualization of the compression projection for LLaVA-1.5-7b on MT-GQA with the compression rate of 90%.
Figure 7: Visualization of the compression projection for LLaVA-1.5-13b on MT-GQA with the compression rate of 90%.
Vision-language models (VLMs) have achieved remarkable multimodal understanding and reasoning capabilities, yet remain computationally expensive due to dense visual tokenization. Existing efficiency approaches either merge redundant visual tokens or drop them progressively in language backbone, often trading accuracy for speed. In this work, we propose DUET-VLM, a versatile plug-and-play dual compression framework that consists of (a) vision-only redundancy aware compression of vision encoder's output into information-preserving tokens, followed by (b) layer-wise, salient text-guided dropping of visual tokens within the language backbone to progressively prune less informative tokens. This coordinated token management enables aggressive compression while retaining critical semantics. On LLaVA-1.5-7B, our approach maintains over 99% of baseline accuracy with 67% fewer tokens, and still retains >97% even at 89% reduction. With this dual-stage compression during training, it achieves 99.7% accuracy at 67% and 97.6% at 89%, surpassing prior SoTA visual token reduction methods across multiple benchmarks. When integrated into Video-LLaVA-7B, it even surpasses the baseline -- achieving >100% accuracy with a substantial 53.1% token reduction and retaining 97.6% accuracy under an extreme 93.4% setting. These results highlight end-to-end training with DUET-VLM, enabling robust adaptation to reduced visual (image/video) input without sacrificing accuracy, producing compact yet semantically rich representations within the same computational budget. Our code is available at https://github.com/AMD-AGI/DUET-VLM.
Large Vision-Language Models (LVLMs) incur substantial inference costs due to the processing of a vast number of visual tokens. Existing methods typically struggle to model progressive visual token reduction as a multi-step decision process with sequential dependencies and often rely on hand-engineered scoring rules that lack adaptive optimization for complex reasoning trajectories. To overcome these limitations, we propose TPRL, a reinforcement learning framework that learns adaptive pruning trajectories through language-guided sequential optimization tied directly to end-task performance. We formulate visual token pruning as a sequential decision process with explicit state transitions and employ a self-supervised autoencoder to compress visual tokens into a compact state representation for efficient policy learning. The pruning policy is initialized through learning from demonstrations and subsequently fine-tuned using Proximal Policy Optimization (PPO) to jointly optimize task accuracy and computational efficiency. Our experimental results demonstrate that TPRL removes up to 66.7% of visual tokens and achieves up to a 54.2% reduction in FLOPs during inference while maintaining a near-lossless average accuracy drop of only 0.7%. Code is released at mypink{https://github.com/MagicVicCoder/TPRL}.
Sihan Cao, Jianwei Zhang, Pengcheng Zheng +7
School of Computer Science and Engineering, University of Electronic Science and Technology of China, Chengdu, China · School of Robotics and Advanced Manufacture, Harbin Institute of Technology, Shenzhen, China · College of Information and Control Engineering, Xi’an University of Architecture and Technology, Xi’an, China
Large Vision-Language Models achieve strong VQA performance, but processing high-resolution, information-rich images requires substantial computation, motivating visual token reduction. However, existing methods often prune individual tokens or rely on fixed-size cropping, limiting their ability to preserve spatially structured information such as horizontally or vertically elongated text. To address this limitation, we propose ReFIT, an instruction-guided visual token reduction framework for efficient LVLM inference. ReFIT consists of Relevance-Guided Window Reshaping (RWR) and Instruction-Guided Token Refinement (ITR), where RWR captures instruction-relevant regions by adapting to their spatial characteristics, while ITR further removes unnecessary visual tokens. Experiments on four VQA benchmarks demonstrate that ReFIT improves answer accuracy while reducing computational cost, and qualitative results demonstrate its effectiveness in localizing relevant regions and removing unnecessary visual information.
Seyoung Jeong, Jong Pil Yun, Sang Jun Lee
Jeonbuk National University, Jeonju, Republic of Korea · Korea Institute of Industrial Technology (KITECH), Incheon, Republic of Korea · Chung-Ang University, Seoul, Republic of Korea