A system for buffering an application image to be displayed on a display device; the system comprising: a processor connectable with the display device and arranged to provide the application image separated into a plurality of tiles, wherein each of the tiles identifies a corresponding area of the application image; and a computer-readable memory comprising: a set of tile buffers; a composition manager arranged to associate each tile buffer either with a front buffer or a back buffer thereby indicating which of the tile buffers are included in each of the front and back buffers (122, 126); the composition manager being further arranged to determine which of the tiles of the application image are overlapped by a viewport, which viewport identifies a visible portion of the application image, the visible portion being smaller than the application image, wherein the composition manager is arranged to allocate the back buffer to be suitable for storing the tiles of the application image which are overlapped by the viewport and tiles of the application image which are not overlapped by the viewport in the tile buffers associated with the back buffer and so that each tile buffer associated with the back buffer is suitable to store a corresponding tile of the application image; and wherein the composition manager is arranged to allocate the front buffer so that each tile buffer associated with the front buffer is suitable to store a corresponding tile of the application image and so that the front buffer is suitable for storing only the corresponding tiles of the application image which are overlapped by the viewport; and wherein said system is further configured for reading said visible portion from the front buffer for display; the composition manager being further configured to swap, in response to a buffer flip, the set of tile buffers associated with the front buffer with some tile buffers of the set of tile buffers associated with the back buffer, wherein the tile buffers that are swapped store the tiles of the application image overlapped by the viewport but not the tiles of the application image not overlapped by the viewport; the composition manager being further configured to adjust, when the viewport moves, which of a plurality of tile buffers are in the front buffer by including in the front buffer those tile buffers associated with the back buffer that correspond to the tiles of the application image newly overlapped by the viewport; wherein the system is arranged to render the application image into the back buffer before each buffer swap. a processor connectable with the display device and arranged to provide the application image separated into a plurality of tiles, wherein each of the tiles identifies a corresponding area of the application image; and a computer-readable memory comprising: a set of tile buffers; a composition manager arranged to associate each tile buffer either with a front buffer or a back buffer thereby indicating which of the tile buffers are included in each of the front and back buffers (122, 126); the composition manager being further arranged to determine which of the tiles of the application image are overlapped by a viewport, which viewport identifies a visible portion of the application image, the visible portion being smaller than the application image, wherein the composition manager is arranged to allocate the back buffer to be suitable for storing the tiles of the application image which are overlapped by the viewport and tiles of the application image which are not overlapped by the viewport in the tile buffers associated with the back buffer and so that each tile buffer associated with the back buffer is suitable to store a corresponding tile of the application image; and wherein the composition manager is arranged to allocate the front buffer so that each tile buffer associated with the front buffer is suitable to store a corresponding tile of the application image and so that the front buffer is suitable for storing only the corresponding tiles of the application image which are overlapped by the viewport; a set of tile buffers; a composition manager arranged to associate each tile buffer either with a front buffer or a back buffer thereby indicating which of the tile buffers are included in each of the front and back buffers (122, 126); the composition manager being further arranged to determine which of the tiles of the application image are overlapped by a viewport, which viewport identifies a visible portion of the application image, the visible portion being smaller than the application image, wherein the composition manager is arranged to allocate the back buffer to be suitable for storing the tiles of the application image which are overlapped by the viewport and tiles of the application image which are not overlapped by the viewport in the tile buffers associated with the back buffer and so that each tile buffer associated with the back buffer is suitable to store a corresponding tile of the application image; and wherein the composition manager is arranged to allocate the front buffer so that each tile buffer associated with the front buffer is suitable to store a corresponding tile of the application image and so that the front buffer is suitable for storing only the corresponding tiles of the application image which are overlapped by the viewport;