I have just left a job, and am about to start a new one, but just before I left one of the other guys in my team was tasked with writing something using the Lucene search engine for .NET. We had to search across 300,000 or some objects and it appeared to be pretty quick. We were doing it in response to a user typing a character, and no delay was not noticeable at all, even though it was going through loads of Rx and loads of different application layers, and finally hitting Lucene to search for results.
This spiked my interest a bit and I decided to give Lucene a try and see if I could some up with a simple demo that I could share.
So that is what I did and the results of that can be found at this article: