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Optimisation of Local Retrieval-Augmented Generation (RAG) Systems on Consumer-Grade Hardware

Oleksandra Annawitt

FH JOANNEUM ePUB, 2026

Abstract

Managing confidential data in high-security sectors creates a critical conflict between privacy and productivity: organizations must either risk data sovereignty using cloud-based Large Language Models (LLMs) or accept inefficient, manual workflows. While local, offline Retrieval-Augmented Generation (RAG) pipelines offer a secure alternative, deploying them on consumer-grade hardware introduces severe performance bottlenecks during document ingestion, retrieval and generation. Furthermore, the lack of standardized benchmarks to quantify trade-offs between speed and accuracy leaves developers without clear architectural guidance.To address this gap, this study systematically evaluates local RAG performance under the hardware constraints using a quantitative and qualitative experimental framework. The research utilises a 2x4x2x3 factorial design comprising 48 unique experimental conditions. It cross-evaluates two different document structures — a 144-page hierarchical legal document and a 25-page tabular financial report — across four document loaders (PyMuPDF4LLM, openDataLoader, PDFPlumberLoader and UnstructuredPDFLoader), two open-source embedding models (Nomic-Embed-Text and BGE-M3) and three chunking strategies (Fixed-Size, Recursive and Semantic). Processing speeds are captured across separate pipeline stages, while informational accuracy and retrieval quality are assessed using the automated RAGAS framework.The experimental results reveal that document structure…

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