throttling to 60ms to prevent overlapping

src/jquery.gridster.js

@@ -399,7 +399,7 @@
             drag: throttle(function(event, ui) {
                 self.on_drag.call(self, event, ui);
                 self.$el.trigger('gridster:drag');
-            }, 130)
+            }, 60)
           });
 
         this.drag_api = this.$el.draggable(draggable_options).data('draggable');