Why do you use pgvector instead of pgANN? My understanding is pgANN is built with FAISS. When I compared pgvector with FAISS, pgvector was 3-5x slower.
A marqo.ai dev is currently working on adding HNSW-IVF and HNSW support https://news.ycombinator.com/item?id=35551684 and the maintainer has recently noted that they are actively working on an IVFPQ/ScaNN implementation https://github.com/pgvector/pgvector/issues/93
The pgAnn creator actually asked about performance a month ago here https://github.com/pgvector/pgvector/issues/58
Expect to see performance improve dramatically later this year.