The pointy white vaulting which was built over the nave mid C13th seems very weak compared to the elephantine romanesque pillars and triforium of a century or so earlier. It is sobering that fashion must have been rife in those days and fortunate that some cathedrals avoided this type of intrusion into the spaciousness of the nave (eg Ely http://www.pbase.com/crisscross/image/151587603 and St Alban's http://www.pbase.com/crisscross/image/136932874 )