read_file tool takes 15-20 seconds, normal?

15-20s is high. Normal is 1-3s for a cached file, 5-8s for a cold-start Lambda + S3 fetch.

If you're consistently seeing 15-20s, it's probably the RAG reindex kicking in on cold start. There's a flag that was left enabled on some older tenants: RAG_STARTUP_REINDEX_ENABLED. We disabled it by default a few releases ago - it was rebuilding the vector index every cold start even when nothing had changed.

Go to Settings > Advanced > Performance and check if Startup Reindex is on. Turn it off. Reindex now only happens after KB imports and on explicit trigger.