5. The method of claim 1 , wherein the plurality of performance metrics comprises: a ‘first visit’ score, wherein the first visit score assumes a visitor has not been to the Web page before or that the visitor's cache has been emptied; a ‘second visit’ score, wherein the second visit score assumes the visitor has previously visited the Web page and is revisiting after the time specified by a Revisit Time parameter; a ‘total’ score, wherein the total score is calculated from the time required to load all files required by the Web page; and a ‘blocking score’, wherein the blocking score is calculated solely from files which may potentially block display of a page until said files are completely downloaded, said blocking score serving to give a measure of how quickly a user experiences some feedback representing that the Web page is loading.
5. The method of claim 1 , wherein the plurality of performance metrics comprises: a ‘first visit’ score, wherein the first visit score assumes a visitor has not been to the Web page before or that the visitor's cache has been emptied; a ‘second visit’ score, wherein the second visit score assumes the visitor has previously visited the Web page and is revisiting after the time specified by a Revisit Time parameter; a ‘total’ score, wherein the total score is calculated from the time required to load all files required by the Web page; and a ‘blocking score’, wherein the blocking score is calculated solely from files which may potentially block display of a page until said files are completely downloaded, said blocking score serving to give a measure of how quickly a user experiences some feedback representing that the Web page is loading. 6. The method of claim 5 , wherein values for each of the first visit score and the second visit score are reported for each of the total score and the blocking score, wherein the scores are aggregated to result in said page score.