diff --git a/platform/usageView/src/com/intellij/usages/impl/Node.java b/platform/usageView/src/com/intellij/usages/impl/Node.java
index a2663621486a..efca5fabef99 100644
--- a/platform/usageView/src/com/intellij/usages/impl/Node.java
+++ b/platform/usageView/src/com/intellij/usages/impl/Node.java
@@ -17,6 +17,7 @@ package com.intellij.usages.impl;
 
 import com.intellij.openapi.util.Comparing;
 import com.intellij.usages.UsageView;
+import org.intellij.lang.annotations.MagicConstant;
 import org.jetbrains.annotations.NotNull;
 
 import javax.swing.tree.DefaultMutableTreeNode;
@@ -26,11 +27,28 @@ import javax.swing.tree.DefaultTreeModel;
  * @author max
  */
 public abstract class Node extends DefaultMutableTreeNode {
-  private boolean myIsValid = true;
   protected final DefaultTreeModel myTreeModel;
-  private Boolean myIsReadOnly = null;
-  private boolean myExcluded = false;
-  private String myText = null;
+  private String myText;
+
+  private byte flags;
+  private static final int INVALID_FLAG = 0;
+  private static final int READ_ONLY_FLAG = 1;
+  private static final int READ_ONLY_COMPUTED_FLAG = 2;
+  private static final int EXCLUDED_FLAG = 3;
+  private static final int UPDATED_FLAG = 4;
+
+  @MagicConstant(intValues = {INVALID_FLAG, READ_ONLY_FLAG, READ_ONLY_COMPUTED_FLAG, EXCLUDED_FLAG, UPDATED_FLAG})
+  @interface FlagConstant {}
+
+  private boolean isFlagSet(@FlagConstant int flag) {
+    int state = flags >> flag;
+    return (state & 1) != 0;
+  }
+
+  private void setFlag(@FlagConstant int flag, boolean value) {
+    int state = value ? 1 : 0;
+    flags = (byte)(flags & ~(1 << flag) | state << flag);
+  }
 
   protected Node(@NotNull DefaultTreeModel model) {
     myTreeModel = model;
@@ -44,35 +62,57 @@ public abstract class Node extends DefaultMutableTreeNode {
   protected abstract boolean isDataValid();
   protected abstract boolean isDataReadOnly();
   protected abstract boolean isDataExcluded();
-  protected abstract String getText(UsageView view);
+  protected abstract String getText(@NotNull UsageView view);
 
   public final boolean isValid() {
-    return myIsValid;
+    return !isFlagSet(INVALID_FLAG);
   }
 
   public final boolean isReadOnly() {
-    if (myIsReadOnly == null) myIsReadOnly = Boolean.valueOf(isDataReadOnly());
-    return myIsReadOnly.booleanValue();
+    boolean result;
+    boolean computed = isFlagSet(READ_ONLY_COMPUTED_FLAG);
+    if (computed) {
+      result = isFlagSet(READ_ONLY_FLAG);
+    }
+    else {
+      result = isDataReadOnly();
+      setFlag(READ_ONLY_COMPUTED_FLAG, true);
+      setFlag(READ_ONLY_FLAG, result);
+    }
+    return result;
   }
 
   public final boolean isExcluded() {
-    return myExcluded;
+    return isFlagSet(EXCLUDED_FLAG);
   }
 
-  public final void update(UsageView view) {
+  public final void update(@NotNull UsageView view) {
     boolean isDataValid = isDataValid();
     boolean isReadOnly = isDataReadOnly();
     boolean isExcluded = isDataExcluded();
     String text = getText(view);
-    if (isDataValid != myIsValid || myIsReadOnly == null || isReadOnly != myIsReadOnly.booleanValue() || isExcluded != myExcluded ||
-      !Comparing.equal(myText, text)) {
-      myIsValid = isDataValid;
-      myExcluded = isExcluded;
-      myIsReadOnly = Boolean.valueOf(isReadOnly);
+
+    boolean cachedValid = isValid();
+    boolean cachedExcluded = isFlagSet(EXCLUDED_FLAG);
+    boolean cachedReadOnly = isFlagSet(READ_ONLY_FLAG);
+
+    if (isDataValid != cachedValid || isReadOnly != cachedReadOnly || isExcluded != cachedExcluded || !Comparing.equal(myText, text)) {
+      setFlag(INVALID_FLAG, !isDataValid);
+      setFlag(READ_ONLY_FLAG, isReadOnly);
+      setFlag(EXCLUDED_FLAG, isExcluded);
+
       myText = text;
       updateNotify();
       myTreeModel.nodeChanged(this);
     }
+    setFlag(UPDATED_FLAG, true);
+  }
+
+  public void markNeedUpdate() {
+    setFlag(UPDATED_FLAG, false);
+  }
+  public boolean needsUpdate() {
+    return !isFlagSet(UPDATED_FLAG);
   }
 
   /**
diff --git a/platform/usageView/src/com/intellij/usages/impl/UsageViewImpl.java b/platform/usageView/src/com/intellij/usages/impl/UsageViewImpl.java
index 95354cb16be0..8825c3746be7 100644
--- a/platform/usageView/src/com/intellij/usages/impl/UsageViewImpl.java
+++ b/platform/usageView/src/com/intellij/usages/impl/UsageViewImpl.java
@@ -65,10 +65,7 @@ import org.jetbrains.annotations.NotNull;
 import org.jetbrains.annotations.Nullable;
 
 import javax.swing.*;
-import javax.swing.event.ChangeEvent;
-import javax.swing.event.ChangeListener;
-import javax.swing.event.TreeSelectionEvent;
-import javax.swing.event.TreeSelectionListener;
+import javax.swing.event.*;
 import javax.swing.tree.*;
 import java.awt.*;
 import java.awt.datatransfer.StringSelection;
@@ -143,10 +140,10 @@ public class UsageViewImpl implements UsageView, UsageModelTracker.UsageModelTra
   private final Object lock = new Object();
   private Splitter myPreviewSplitter;
 
-  public UsageViewImpl(@NotNull final Project project,
-                       @NotNull UsageViewPresentation presentation,
-                       @NotNull UsageTarget[] targets,
-                       Factory<UsageSearcher> usageSearcherFactory) {
+  UsageViewImpl(@NotNull final Project project,
+                @NotNull UsageViewPresentation presentation,
+                @NotNull UsageTarget[] targets,
+                Factory<UsageSearcher> usageSearcherFactory) {
     myPresentation = presentation;
     myTargets = targets;
     myUsageSearcherFactory = usageSearcherFactory;
@@ -416,6 +413,24 @@ public class UsageViewImpl implements UsageView, UsageModelTracker.UsageModelTra
 
     TreeUtil.selectFirstNode(myTree);
     PopupHandler.installPopupHandler(myTree, IdeActions.GROUP_USAGE_VIEW_POPUP, ActionPlaces.USAGE_VIEW_POPUP);
+
+    myTree.addTreeExpansionListener(new TreeExpansionListener() {
+      @Override
+      public void treeExpanded(TreeExpansionEvent event) {
+        TreePath path = event.getPath();
+        Object component = path.getLastPathComponent();
+        if (!(component instanceof Node)) return;
+        Node node = (Node)component;
+        if (node.needsUpdate()) {
+          checkNodeValidity(node, path);
+        }
+      }
+
+      @Override
+      public void treeCollapsed(TreeExpansionEvent event) {
+      }
+    });
+
     //TODO: install speed search. Not in openapi though. It makes sense to create a common TreeEnchancer service.
   }
 
@@ -541,7 +556,6 @@ public class UsageViewImpl implements UsageView, UsageModelTracker.UsageModelTra
       actionsManager.createPrevOccurenceAction(myRootPanel),
       actionsManager.createNextOccurenceAction(myRootPanel),
       actionsManager.installAutoscrollToSourceHandler(myProject, myTree, new MyAutoScrollToSourceOptionProvider()),
-      //createImportToFavorites(),
       actionsManager.createExportToTextFileAction(myTextFileExporter),
       actionsManager.createHelpAction(HELP_ID)
     };
@@ -906,7 +920,8 @@ public class UsageViewImpl implements UsageView, UsageModelTracker.UsageModelTra
 
   private void updateImmediately() {
     if (myProject.isDisposed()) return;
-    checkNodeValidity((DefaultMutableTreeNode)myTree.getModel().getRoot());
+    TreeNode root = (TreeNode)myTree.getModel().getRoot();
+    checkNodeValidity(root, new TreePath(root));
     updateOnSelectionChanged();
   }
 
@@ -917,12 +932,20 @@ public class UsageViewImpl implements UsageView, UsageModelTracker.UsageModelTra
     }
   }
 
-  private void checkNodeValidity(@NotNull DefaultMutableTreeNode node) {
-    Enumeration enumeration = node.children();
-    while (enumeration.hasMoreElements()) {
-      checkNodeValidity((DefaultMutableTreeNode)enumeration.nextElement());
+  private void checkNodeValidity(@NotNull TreeNode node, @NotNull TreePath path) {
+    if (node instanceof Node && node != getModelRoot()) {
+      ((Node)node).update(this);
+    }
+    if (myTree.isCollapsed(path)) {
+      if (node instanceof Node) {
+        ((Node)node).markNeedUpdate();
+      }
+      return; // optimization: do not call expensive update() on invisible node
+    }
+    for (int i=0; i < node.getChildCount(); i++) {
+      TreeNode child = node.getChildAt(i);
+      checkNodeValidity(child, path.pathByAddingChild(child));
     }
-    if (node instanceof Node && node != getModelRoot()) ((Node)node).update(this);
   }
 
   private void updateLater() {