Optimise array controller addObject: by eliminating entirely pointless rearrange when added objects did not pass the filter. Also avoided double rearrange if clearsFilterPredicateOnInsertion.

CPArrayControllerPerformance.j execution time on "testAddObject_, sorted, filtered" down from ~420ms to ~60ms on my machine.

AppKit/CPArrayController.j

@@ -719,8 +719,12 @@
     if (![self canAdd])
         return;
 
-    if (_clearsFilterPredicateOnInsertion)
+    var willClearPredicate = NO;
+    if (_clearsFilterPredicateOnInsertion && _filterPredicate)
+    {
         [self willChangeValueForKey:@"filterPredicate"];
+        willClearPredicate = YES;
+    }
 
     [self willChangeValueForKey:@"content"];
 
@@ -735,11 +739,15 @@
     [_contentObject addObject:object];
     _disableSetContent = NO;
 
-    if (_clearsFilterPredicateOnInsertion)
-        [self __setFilterPredicate:nil];
-
-    if (_filterPredicate === nil || [_filterPredicate evaluateWithObject:object])
+    if (willClearPredicate)
     {
+        // Full rearrange needed due to changed filter.
+        _filterPredicate = nil;
+        [self _rearrangeObjects];
+    }
+    else if (_filterPredicate === nil || [_filterPredicate evaluateWithObject:object])
+    {
+        // Insert directly into the array.
         var pos = [_arrangedObjects insertObject:object inArraySortedByDescriptors:_sortDescriptors];
 
         // selectionIndexes change notification will be fired as a result of the
@@ -749,12 +757,16 @@
         else
             [_selectionIndexes shiftIndexesStartingAtIndex:pos by:1];
     }
-    else
-        [self _rearrangeObjects];
+    /*
+    else if (_filterPredicate !== nil)
+    ...
+    // Implies _filterPredicate && ![_filterPredicate evaluateWithObject:object], so the new object does
+    // not appear in arrangedObjects and we do not have to update at all.
+    */
 
     // This will also send notificaitons for arrangedObjects.
     [self didChangeValueForKey:@"content"];
-    if (_clearsFilterPredicateOnInsertion)
+    if (willClearPredicate)
         [self didChangeValueForKey:@"filterPredicate"];
 }