I think some people also want timely results. I certainly do.
Ideally, yes, but that doesn't appear to be an option. Given the choice between instant and incomplete results, and slightly slower but complete results, I'll take the latter.
Considering the difference in speed, it's faster for me to find what I was looking for by sifting through GMail's results, than to wait for Outlook's results to show up at all. Outlook's search essentially renders my whole machine useless until it's done searching.