I don't know if this has been posted somewhere here, but there is a thread over at MacNN on compressing the window buffers and getting some extra speed out of this.
http://newforums.macnn.com/cgi-bin/ultimatebb.cgi?ubb=get_topic&f=46&t=000100
http://newforums.macnn.com/cgi-bin/ultimatebb.cgi?ubb=get_topic&f=46&t=000100