Dev.to
7/19/2026

Optimizing RAG at Scale: Chunking, Hybrid Retrieval, and Reranking That Cut Latency 40%
Original: Optimizing RAG at Scale: Chunking, Retrieval, and the Bayesian Search That Cut Latency 40%
Short summary
A detailed engineering walkthrough of rebuilding a RAG retrieval layer for production, covering chunking strategies by document type, hybrid retrieval combining vector search and BM25 with reciprocal rank fusion, and cross-encoder reranking. The author reports achieving 95% recall@10 and 40% latency reduction through query transformation, parallel retrieval, and a 50-to-5 rerank funnel. Includes production config tables and Python code for each pipeline stage.
- •Chunking strategy should vary by document type: recursive for legal, semantic for conversations, agentic for complex wikis
- •Hybrid retrieval (vector + BM25 + cross-encoder rerank) via Reciprocal Rank Fusion beats pure vector or keyword search
- •Cross-encoder rerank costs 50ms but gains 15% recall; query transformation improves retrieval for poorly-formed user queries
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