When should you use a reranker versus hybrid search alone?

Hybrid search improves recall cheaply by combining two retrievers, so use it as a baseline for almost every production RAG system. Add a reranker on top when you need higher precision in the final top-k passed to the language model, especially when context window cost or generation latency forces you to pass only three to five chunks. Rerankers add 20 to 200 milliseconds of latency per query and require a GPU or managed service, so the cost-benefit depends on traffic volume. Both together is the 2026 production default.