My mind is slipping but we used to have a global cache of elements that had events bound but that caused memory leaks and worse performance in large pages.

I've been thinking about something that might speed this up.

Adding a selector filter called ':bound' that returns $.data( elem, 'handle' );

and then doing $('*:bound').unbind().

So, instead of going with an .each and then the unbind for each node, we filter with a native loop (inside $.filter) and we only call unbind on those that is neccessary.

I propose using the jQuery internal cache to unbind events, instead of traversing all elements.

jQuery(window).bind("unload", function() {
   // jQuery("*").add(document).unbind(); // old
   for ( var guid in jQuery.cache ) // iterate the cache
      if ( guid>1 && jQuery.cache[ guid ].handle ) // not window ( guid==1 )
         jQuery.event.remove( jQuery.cache[ guid ].handle.elem ); 
   });

This addition should sufficiently clean-up any stored data as well...

jQuery( window ).bind( "unload", function(){
	for ( var id in jQuery.cache ){ // iterate the cache
		if ( id>1 && jQuery.cache[ id ].handle ) // bound non-window events
			jQuery.event.remove( jQuery.cache[ id ].handle.elem ); // unbind()
		if ( id!=1 ) delete jQuery.cache[ id ]; // removeData()
		}
	});