A web page may be rendered for display on a client device. The rendered web page may be based on a first document. It may be determined that (i) a scroll position of the rendered web page has changed such that the scroll position is below a threshold scroll position, and (ii) the change of the scroll position is due to an event other than receiving a scrolling command from a user. Possibly responsive to this determination, a second document may be requested and received from a content server device. The web page may be re-rendered for display on the client device. The re-rendered web page may include content from the first document and content from the second document.