[#30274] JFormValidator JavaScript class does not scale well

Joomla!'s JFormValidator JavaScript class does not scale well with large numbers
of form elements. The reason for this is that the handleResponse() method loops
through every label each time it is called. Instead of this, I have modified
the code to do this only once and store the results for future use.

Here is the relevant forum post:
http://forum.joomla.org/viewtopic.php?p=3002410#p3002410

Here is the issue tracker:
http://joomlacode.org/gf/project/joomla/tracker/?action=TrackerItemEdit&tracker_id=8103&tracker_item_id=30274