A computer-implemented method is disclosed which comprises the steps of receiving a request for glyphs, the request identifying a font and characters of the font that are required, and searching for at least one superset of glyphs that contain the required glyphs and are absent of other glyphs of the font. The method further operates so that, if at least one superset is found, it returns the or a selected superset in reply to the request. Otherwise, if at least one superset is not found, a superset of glyphs that contain the required glyphs is compiled and returned in reply to the request, and the new superset is stored in a cache. A system configured to perform said method steps is also disclosed.