--- docshell/base/nsWebShell.cpp.orig	2006-01-24 21:46:02.000000000 -0500
+++ docshell/base/nsWebShell.cpp	2006-01-24 23:17:35.000000000 -0500
@@ -99,6 +99,7 @@
 #include "nsIFocusController.h"
 #include "nsGUIEvent.h"
 #include "nsISHistoryInternal.h"
+#include "nsCheapSets.h"
 
 #include "nsIHttpChannel.h"
 #include "nsIHttpChannelInternal.h"
@@ -327,6 +328,11 @@
   const PRUnichar *start = value.BeginReading();
   const PRUnichar *end   = value.EndReading();
   const PRUnichar *iter  = start;
+
+  nsStringHashSet *uriHash = new nsStringHashSet();
+  NS_ASSERTION(uriHash, "Out of memory");
+  uriHash->Init(10);
+
   for (;;) {
     if (iter < end && *iter != ' ') {
       ++iter;
@@ -334,12 +340,17 @@
       while (*start == ' ' && start < iter)
         ++start;
       if (iter != start)
-        SendPing(Substring(start, iter), doc, referrer, ios);
+        if (!uriHash->Contains(Substring(start, iter))) {
+          SendPing(Substring(start, iter), doc, referrer, ios);
+          uriHash->Put(Substring(start, iter));
+        }
       start = iter = iter + 1;
       if (iter >= end)
         break;
     }
   }
+
+  delete uriHash;
 }
 
 //----------------------------------------------------------------------