diff --git a/ChangeLog b/ChangeLog
index a8d512c80d..1913ad7b50 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,8 +1,17 @@
+2008-07-22  Sven Neumann  <sven@gimp.org>
+
+	* app/base/gimphistogram.[ch]: added new method
+	gimp_histogram_duplicate().
+
+	* app/widgets/gimphistogrameditor.c
+	(gimp_histogram_editor_frozen_update): instead of recalculating
+	the histogram, use a duplicate for the background histogram.
+
 2008-07-22  Sven Neumann  <sven@gimp.org>
 
 	* app/widgets/gimphistogrameditor.c (gimp_histogram_editor_set_image):
 	reverted last change, it did not plug the leak.
-	
+
 2008-07-22  Sven Neumann  <sven@gimp.org>
 
 	* app/gui/session.c (session_init): plugged a small memory leak.
diff --git a/app/base/gimphistogram.c b/app/base/gimphistogram.c
index 02bc251fd7..ca65c00e74 100644
--- a/app/base/gimphistogram.c
+++ b/app/base/gimphistogram.c
@@ -102,6 +102,39 @@ gimp_histogram_unref (GimpHistogram *histogram)
     }
 }
 
+/**
+ * gimp_histogram_duplicate:
+ * @histogram: a %GimpHistogram
+ *
+ * Creates a duplicate of @histogram. The duplicate has a reference
+ * count of 1 and contains the values from @histogram.
+ *
+ * Return value: a newly allocated %GimpHistogram
+ **/
+GimpHistogram *
+gimp_histogram_duplicate (GimpHistogram *histogram)
+{
+  GimpHistogram *dup;
+
+  g_return_val_if_fail (histogram != NULL, NULL);
+
+  dup = gimp_histogram_new ();
+
+#ifdef ENABLE_MP
+  g_static_mutex_lock (&histogram->mutex);
+#endif
+
+  dup->n_channels = histogram->n_channels;
+  dup->values[0]  = g_memdup (histogram->values[0],
+                              sizeof (gdouble) * dup->n_channels * 256);
+
+#ifdef ENABLE_MP
+  g_static_mutex_unlock (&histogram->mutex);
+#endif
+
+  return dup;
+}
+
 void
 gimp_histogram_calculate (GimpHistogram *histogram,
                           PixelRegion   *region,
diff --git a/app/base/gimphistogram.h b/app/base/gimphistogram.h
index 5e812defd4..2f847ab647 100644
--- a/app/base/gimphistogram.h
+++ b/app/base/gimphistogram.h
@@ -23,9 +23,12 @@
 
 
 GimpHistogram * gimp_histogram_new           (void);
+
 GimpHistogram * gimp_histogram_ref           (GimpHistogram        *histogram);
 void            gimp_histogram_unref         (GimpHistogram        *histogram);
 
+GimpHistogram * gimp_histogram_duplicate     (GimpHistogram        *histogram);
+
 void            gimp_histogram_calculate     (GimpHistogram        *histogram,
                                               PixelRegion          *region,
                                               PixelRegion          *mask);
diff --git a/app/widgets/gimphistogrameditor.c b/app/widgets/gimphistogrameditor.c
index ff580b1efe..20b2a81343 100644
--- a/app/widgets/gimphistogrameditor.c
+++ b/app/widgets/gimphistogrameditor.c
@@ -365,6 +365,24 @@ gimp_histogram_editor_layer_changed (GimpImage           *image,
   gimp_histogram_editor_name_update (editor);
 }
 
+static gboolean
+gimp_histogram_editor_validate (GimpHistogramEditor *editor)
+{
+  if (! editor->valid && editor->histogram)
+    {
+      if (editor->drawable)
+        gimp_drawable_calculate_histogram (editor->drawable, editor->histogram);
+      else
+        gimp_histogram_calculate (editor->histogram, NULL, NULL);
+
+      gimp_histogram_editor_info_update (editor);
+
+      editor->valid = TRUE;
+    }
+
+  return editor->valid;
+}
+
 static void
 gimp_histogram_editor_frozen_update (GimpHistogramEditor *editor,
                                      const GParamSpec    *pspec)
@@ -375,10 +393,8 @@ gimp_histogram_editor_frozen_update (GimpHistogramEditor *editor,
     {
       if (! editor->bg_histogram)
         {
-          editor->bg_histogram = gimp_histogram_new ();
-
-          gimp_drawable_calculate_histogram (editor->drawable,
-                                             editor->bg_histogram);
+          if (gimp_histogram_editor_validate (editor))
+            editor->bg_histogram = gimp_histogram_duplicate (editor->histogram);
 
           gimp_histogram_view_set_background (view, editor->bg_histogram);
         }
@@ -538,17 +554,7 @@ gimp_histogram_editor_info_update (GimpHistogramEditor *editor)
 static gboolean
 gimp_histogram_view_expose (GimpHistogramEditor *editor)
 {
-  if (! editor->valid && editor->histogram)
-    {
-      if (editor->drawable)
-        gimp_drawable_calculate_histogram (editor->drawable, editor->histogram);
-      else
-        gimp_histogram_calculate (editor->histogram, NULL, NULL);
-
-      editor->valid = TRUE;
-
-      gimp_histogram_editor_info_update (editor);
-    }
+  gimp_histogram_editor_validate (editor);
 
   return FALSE;
 }