1. A method for rendering a page description language (PDL) document, the method comprising: receiving a plurality of display lists, each display list comprising a plurality of display list objects; determining a repeated sequence of a predetermined number of consecutive display list objects across the display lists; determining a reusable sequence of display list objects, for the repeated sequence, by extending the repeated sequence to further consecutive display list objects, each occurrence of the reusable sequence being associated with a z-order position in a corresponding display list; subdividing at least one display list, at the z-order position of the reusable sequence in said display list, into a plurality of z-bands including a reusable z-band for the determined reusable sequence; generating a reusable intermediate graphical representation for the determined reusable sequence and a further intermediate graphical representation for at least one other z-band; merging said further intermediate graphical representation with the reusable intermediate graphical representation in accordance with an order of said z-bands; and rendering the page description language (PDL) document using the merged representations.