Disable scoring in Lucene (.NET)

When searching, is there a way to turn off scoring for any query?

The scenario is that the user refines his request, trying to use different combinations of words, phrases, etc., and needs real-time responses (well, fast enough, at least) for the number of hits.

Search times slow down when scoring hits millions of hits, but the user really doesn't need all of those documents. As soon as he sees that there are 1M + hits, he will start adding additional words to the query. The "Sort by Relevance" option would allow him to do this quickly, while at the same time increasing the points when the number of hits is reasonable.

Is it possible?

I am using Lucene.NET 2.9.2, but AFAIK it is identical to the Java version.