If as you say you _need_ to get pages sequentially then threading appears pointless as the vast majority of the time will be taken getting the data, not processing it. It usually takes 2-4 seconds to get a page. The quantity of processing you can do in this sort of time is huge. I would be extremely suprised if the processing time was more than a few % of the total runtime with the rest of the time simply waiting on the socket for data. You are into much more fruitful territory if you can avoid a sequential get and do at least part of the getting in parallel. Or to put it another way the bottleneck is almost certainly the getting, not the processing. Optimisation that does not affect bottleneck points is pretty much a waste of time.

I suggest you prove that there is any benefit to be gained ie processing takes a significant % of the runtime before you waste your time producing the right solution to the wrong problem.