Manually inline fixed-size list's forEach, to make it possible for the VM to optimize.

runtime/lib/array.dart

 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 
 // TODO(srdjan): Use shared array implementation.
 class _List<E> implements List<E> {
 
   factory _List(length) native "List_allocate";
 
@@ skipping 99 matching lines @@
     return result;
   }
 
   // Iterable interface.
 
   bool contains(Object element) {
     return IterableMixinWorkaround.contains(this, element);
   }
 
   void forEach(f(E element)) {
-    IterableMixinWorkaround.forEach(this, f);
+    for (int i = 0; i < length; i++) {

[kasperl, 2014/08/28 13:45:18]

Does it make a difference if you cache length in a local variable for
unoptimized code?

[Anders Johnsen, 2014/08/28 14:20:12]

Done.

+      f(this[i]);
+    }
   }
 
   String join([String separator = ""]) {
     return IterableMixinWorkaround.joinList(this, separator);
   }
 
   Iterable map(f(E element)) {
     return IterableMixinWorkaround.mapList(this, f);
   }
 
@@ skipping 235 matching lines @@
     return new IterableMixinWorkaround<E>().getRangeList(this, start, end);
   }
 
   // Collection interface.
 
   bool contains(Object element) {
     return IterableMixinWorkaround.contains(this, element);
   }
 
   void forEach(f(E element)) {
     IterableMixinWorkaround.forEach(this, f);

[Lasse Reichstein Nielsen, 2014/08/28 13:47:42]

Consider doing the same thing here.

[Anders Johnsen, 2014/08/28 14:20:12]

Done.

   }
 
   Iterable map(f(E element)) {
     return IterableMixinWorkaround.mapList(this, f);
   }
 
   String join([String separator = ""]) {
     return IterableMixinWorkaround.joinList(this, separator);
   }
 
@@ skipping 169 matching lines @@
     }
     _position = _length;
     _current = null;
     return false;
   }
 
   E get current {
     return _current;
   }
 }