It's linked to other questions/requests, but slightly different. I would personally rather that indexing results were persisted between sessions and then updated in the background. As things stand, I have to wait around 3 minutes every time I want to search for something, which disrupts the workflow. I would much rather put up with cached results that were displayed immediately, whilst being refined in the background.
You could also use some more advanced operators (eg '-' for exclusions etc)