Perhaps you could preload the content but not push it into the page. Then provide some kind of a visual indicator that new content is available. A slider on the

Perhaps you could preload the content but not push it into the page. Then provide some kind of a visual indicator that new content is available. A slider on the side of the page that grows with the current position moving down the bar as more new content is available. You could then push that content into the page as they scroll up from the current position. This gives the user the benefit of knowing that there's new content available without the page shifting around the content they are viewing.