Autocomplete: Delay option just delays request, doesn't clear existing timeout, therefore not preventing unncessary requests. Calling abort() on existing requests has no effect for JSONP, but even then its unncessary to start a request if the user is still typing. Works fine in 1-8-stable.

ui/jquery.ui.autocomplete.js

@@ -325,6 +325,7 @@ $.widget( "ui.autocomplete", {
 
 	_searchTimeout: function( event ) {
 		var self = this;
+		clearTimeout( self.searching );
 		self.searching = setTimeout(function() {
 			// only search if the value has changed
 			if ( self.term != self.element.val() ) {
@@ -384,7 +385,7 @@ $.widget( "ui.autocomplete", {
 			this._trigger( "close", event );
 		}
 	},
-	
+
 	_change: function( event ) {
 		if ( this.previous !== this._value() ) {
 			this._trigger( "change", event, { item: this.selectedItem } );