provide relief to sites that are severely impacted by the slow ITEM_UNSEEN searches. This does not incorporate any other flag optimisations as that will require a major DB update and possibly involve significant downtime. This is just to bite off a little chunk now and provide some much needed relief.

include/ItemObject.php

@@ -612,7 +612,7 @@ class Item extends BaseObject {
 				if((! visible_activity($child->data)) || array_key_exists('author_blocked',$child->data)) {
 					continue;
 				}
-				if($child->data['item_flags'] & ITEM_UNSEEN)
+				if(intval($child->data['item_unseen']))
 					$total ++;
 			}
 		}