Netscape probably does have it in their source but the key is that efficiency is the issue. Netscape loses track even seconds after visiting a site. I don't want to download images that I know haven't changed. For example....HUGE title images that are always static!
Can it be implemented to cache pages with keywords such NEXT and so forth? eg. If you are reading a review and there is a link to goto next page. Then get the cache to download the next page while you are still reading the first.
That would be very nice as an integral part of the browser!