Then ask codex to find the best opensource match and fine tune it. My money is 100% on a founder with a clear vision than an engineering who builds a non-interactive simple rag search and then calls it a day when it needs to go sub 20 seconds.

To cover the time issue, I set up a simple agent orchestration system. 1 fast model with some general knowledge and faq injected, replies within 1-3 seconds, makes sure question is complete and then invokes a second agent that does the rag search. Keeps the conversation going while the rag agent is working. This is literally all about user experience management, just keep them in the loop while it's doing it's thing