Scaling local FAISS and LLM RAG system (356k chunks)architectural advice

I’ve been building a local-only AI assistant for security analysis that uses a FAISS vector index and a local model for reasoning over parsed tool output. The current system works well, but I’m running into scaling issues as the dataset grows. Current setup: ~356k chunks FAISS (Flat index) 384-d MiniLM embeddings llama-cpp-python for inference Metadata stored in a single pickle file (~1.5GB) Tool outputs (Nmap/YARA/Volatility/etc.) parsed into structured JSON before querying

Problems I’m running into:

Metadata pickle file loads entirely into RAM

No incremental indexing — have to rebuild the FAISS index from scratch

Query performance degrades with concurrent use

Want to scale to 1M+ chunks but not sure FAISS + pickle is the right long-term architecture

My questions for those who’ve scaled local or offline RAG systems:

How do you store metadata efficiently at this scale?

Is there a practical pattern for incremental FAISS updates?

Would a vector DB (Qdrant, Weaviate, Milvus) be a better fit for offline use?

Any lessons learned from running large FAISS indexes on consumer hardware?

Not looking for product feedback — just architectural guidance from people who’ve built similar systems.