Yes. That's what my code does.

It builds an inverted index of all the content I want to search and then queries that.

It's the searching this index that is the part I need to optimise.

Thanks for the links, however I can't find anything helpfull and low level enough that doesn't only cover the problems I've already solved.. (TBH, I can't find anything with actual code / alogrithms that isn't a back of cigarette packet style demonstration.. My code can already do complex and/or/not searches with arbitary nesting using () in the search and any number of search terms.)