Content rendered for display on a first client device can be referenced for similar pages to be displayed on other client devices such that similar content does not need to be re-rendered. Each client can have a respective virtual rendering engine on a host device, and the content rendered by those virtual engines can be mapped and used to generate content trees for different pages or other groupings of content. When a new page is to be rendered, the tiles or other portions matching previously-rendered tiles can be referenced, so that only new or unique portions need to be rendered for a particular page. The content can come from multiple locations as rendered by multiple virtual clients, such that for many clients the respective virtual engine may not render any content but instead reference rendered content from one or more locations as determined according to the page tree.