1. A method of generating a display list, for use in rendering a document comprising a plurality of glyphs, said method comprising the steps of: (i) setting a directive process a previously unused glyph; (ii) storing said previously unused glyph in said display list as a bitmap representation or as a vector representation, according to the directive, wherein said previously unused glyph is an existing font; (iii) updating the directive based upon a pre-determined criterion; and (iv) repeating steps (ii) and (iii) for at least a subsequent previously unused glyph to generate said display list, wherein said display list is persistent between pages of said document being rendered.