It looks like the results are being loaded with independent ajax requests to each product database. If this was just all done server side, you'd have to wait until all of these requests finished loading instead of having them appear on the page incrementally. Most people don't want to wait 10 seconds for a page to load.
I see. But there must be something more to it, because an asynchronous request shouldn't lock up the browser. Maybe you could use the server as a proxy between the browser and the search-site. It would still load asynchronous, but it would be much swifter. That would also allow you to cache the results for common queries.
