Compressing Large Language Models with PCA Without Performance Loss

Fuente: arXiv
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Main Author: Bengtsson, Magnus
Format: Preprint
Published: 2025
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author Bengtsson, Magnus
author_facet Bengtsson, Magnus
contents We demonstrate that Principal Component Analysis (PCA), when applied in a structured manner, either to polar-transformed images or segment-wise to token sequences, enables extreme compression of neural models without sacrificing performance. Across three case studies, we show that a one-layer classifier trained on PCA-compressed polar MNIST achieves over 98 percent accuracy using only 840 parameters. A two-layer transformer trained on 70-dimensional PCA-reduced MiniLM embeddings reaches 76.62 percent accuracy on the 20 Newsgroups dataset with just 81000 parameters. A decoder-only transformer generates coherent token sequences from 70-dimensional PCA embeddings while preserving over 97 percent cosine similarity with full MiniLM representations, using less than 17 percent of the parameter count of GPT-2. These results highlight PCA-based input compression as a general and effective strategy for aligning model capacity with information content, enabling lightweight architectures across multiple modalities.
format Preprint
id arxiv_https___arxiv_org_abs_2508_04307
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Compressing Large Language Models with PCA Without Performance Loss
Bengtsson, Magnus
Computational Engineering, Finance, and Science
Artificial Intelligence
We demonstrate that Principal Component Analysis (PCA), when applied in a structured manner, either to polar-transformed images or segment-wise to token sequences, enables extreme compression of neural models without sacrificing performance. Across three case studies, we show that a one-layer classifier trained on PCA-compressed polar MNIST achieves over 98 percent accuracy using only 840 parameters. A two-layer transformer trained on 70-dimensional PCA-reduced MiniLM embeddings reaches 76.62 percent accuracy on the 20 Newsgroups dataset with just 81000 parameters. A decoder-only transformer generates coherent token sequences from 70-dimensional PCA embeddings while preserving over 97 percent cosine similarity with full MiniLM representations, using less than 17 percent of the parameter count of GPT-2. These results highlight PCA-based input compression as a general and effective strategy for aligning model capacity with information content, enabling lightweight architectures across multiple modalities.
title Compressing Large Language Models with PCA Without Performance Loss
topic Computational Engineering, Finance, and Science
Artificial Intelligence
url https://arxiv.org/abs/2508.04307