GBrain says vector-only retrieval matches hybrid on top-5 recall at far lower cost

garrytan · x · 2026-07-27

GBrain claims 97.6% recall@5 on the public LongMemEvals benchmark, edging out MemPalace's published 96.6% result on the same dataset.

The screenshot argues that for conversational retrieval, vector-only retrieval is essentially as good as hybrid at top-5, while being much cheaper: around $0.50 per 1,000 queries versus about $3 for a hybrid + LLM expansion setup. The takeaway is that BM25-plus-RRF complexity may not be worth it unless you need higher K or keyword-heavy text.

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