I found a trick frm the OpenFTS mailing list.
using dd < index_filename > /dev/null will cause the index to be added to the operating system file cache. This seems to speed up queries by a couple of orders of magnitude. Average time on OpenACS.org is .5 second for the actual search query.
I am not sure how often you'd have to do this, but it seems to be a good idea.
I'll post how I figured out which file the index is later.
