diff -r 74e2d2f67cfc javafx-ui-common/src/javafx/scene/Node.java
--- a/javafx-ui-common/src/javafx/scene/Node.java	Fri Jul 20 12:44:57 2012 -0700
+++ b/javafx-ui-common/src/javafx/scene/Node.java	Fri Jul 20 15:42:44 2012 -0700
@@ -2102,6 +2102,7 @@
                     if (parent != null) {
                         parent.managedChildChanged();
                     }
+                    notifyManagedChanged();
                 }
 
                 @Override
@@ -2120,6 +2121,13 @@
     }
 
     /**
+     * Called whenever the "managed" flag has changed. This is only
+     * used by Parent as an optimization to keep track of whether a
+     * Parent node is a layout root or not.
+     */
+    void notifyManagedChanged() { }
+
+    /**
      * Defines the x coordinate of the translation that is added to this {@code Node}'s
      * transform for the purpose of layout.  The value should be computed as the
      * offset required to adjust the position of the node from its current
diff -r 74e2d2f67cfc javafx-ui-common/src/javafx/scene/Parent.java
--- a/javafx-ui-common/src/javafx/scene/Parent.java	Fri Jul 20 12:44:57 2012 -0700
+++ b/javafx-ui-common/src/javafx/scene/Parent.java	Fri Jul 20 15:42:44 2012 -0700
@@ -33,8 +33,7 @@
 
 import com.sun.javafx.jmx.MXNodeAlgorithm;
 import com.sun.javafx.jmx.MXNodeAlgorithmContext;
-import javafx.beans.property.ObjectProperty;
-import javafx.beans.property.SimpleObjectProperty;
+import javafx.beans.property.*;
 import javafx.collections.FXCollections;
 import javafx.collections.ListChangeListener.Change;
 import javafx.collections.ObservableList;
@@ -60,8 +59,6 @@
 import com.sun.javafx.sg.PGGroup;
 import com.sun.javafx.sg.PGNode;
 import com.sun.javafx.tk.Toolkit;
-import javafx.beans.property.ReadOnlyBooleanProperty;
-import javafx.beans.property.ReadOnlyBooleanWrapper;
 
 /**
  * The base class for all nodes that have children in the scene graph.
@@ -651,7 +648,7 @@
 
         // If this node is dirty and the new scene is not null
         // then add this node to the new scene's dirty list
-        if (scene != null && awaitingLayout && isLayoutRoot()) {
+        if (scene != null && awaitingLayout && layoutRoot) {
             scene.addToDirtyLayoutList(this);
         }
     }
@@ -700,7 +697,7 @@
     }
 
     @Override boolean isConnected() {
-        return super.isConnected() || isSceneRoot();
+        return super.isConnected() || sceneRoot;
     }
 
     @Override public Node lookup(String selector) {
@@ -824,7 +821,7 @@
             }
 
             setNeedsLayout(true);
-            if (isLayoutRoot()) {
+            if (layoutRoot) {
                 final Scene scene = getScene();
                 if (scene != null) {
                     if (logger.isLoggable(PlatformLogger.FINER)) {
@@ -852,7 +849,7 @@
         prefHeightCache = -1;
         minWidthCache = -1;
         minHeightCache = -1;
-        if (!isLayoutRoot()) {
+        if (!layoutRoot) {
             final Parent parent = getParent();
             if (parent != null) {
                 parent.clearSizeCache();
@@ -1045,13 +1042,25 @@
         }
     }
 
-    boolean isSceneRoot() {
-        final Scene scene = getScene();
-        return scene != null ? scene.getRoot() == this : false;
+    /**
+     * This field is managed by the Scene, and set on any node which is the
+     * root of a Scene.
+     */
+    private boolean sceneRoot = false;
+    final boolean isSceneRoot() { return sceneRoot; }
+    final void updateSceneRoot(boolean value) {
+        this.sceneRoot = value;
+        layoutRoot = !isManaged() || sceneRoot;
     }
 
-    boolean isLayoutRoot() {
-        return !isManaged() || isSceneRoot();
+    /**
+     * Keeps track of whether this node is a layout root. This is updated
+     * whenever the sceneRoot field changes, or whenever the managed
+     * property changes.
+     */
+    private boolean layoutRoot = false;
+    @Override final void notifyManagedChanged() {
+        layoutRoot = !isManaged() || sceneRoot;
     }
 
     /***********************************************************************
diff -r 74e2d2f67cfc javafx-ui-common/src/javafx/scene/Scene.java
--- a/javafx-ui-common/src/javafx/scene/Scene.java	Fri Jul 20 12:44:57 2012 -0700
+++ b/javafx-ui-common/src/javafx/scene/Scene.java	Fri Jul 20 15:42:44 2012 -0700
@@ -991,6 +991,7 @@
                     if (oldRoot != null) {
                         oldRoot.setScene(null);
                         oldRoot.setImpl_traversalEngine(null);
+                        oldRoot.updateSceneRoot(false);
                     }
                     oldRoot = _value;
                     if (_value.getImpl_traversalEngine() == null) {
@@ -998,6 +999,7 @@
                     }
                     _value.getStyleClass().add(0, "root");
                     _value.setScene(Scene.this);
+                    _value.updateSceneRoot(true);
                     markDirty(DirtyBits.ROOT_DIRTY);
                     _value.resize(getWidth(), getHeight()); // maybe no-op if root is not resizable
                     _value.requestLayout();