The HTML parser should lazy attach.

Source/core/dom/CharacterData.cpp

 /*
  * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
  *           (C) 1999 Antti Koivisto (koivisto@kde.org)
  * Copyright (C) 2003, 2004, 2005, 2006, 2007, 2008, 2009 Apple Inc. All rights reserved.
  *
  * This library is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Library General Public
  * License as published by the Free Software Foundation; either
  * version 2 of the License, or (at your option) any later version.
  *
@@ skipping 80 matching lines @@
     if (!characterLengthLimit)
         return 0;
 
     if (string.is8Bit())
         m_data.append(string.characters8() + offset, characterLengthLimit);
     else
         m_data.append(string.characters16() + offset, characterLengthLimit);
 
     ASSERT(!renderer() || isTextNode());
     if (isTextNode())
-        toText(this)->updateTextRenderer(oldLength, 0, DeprecatedAttachNow);
+        toText(this)->updateTextRenderer(oldLength, 0);
 
     document().incDOMTreeVersion();
 
     if (parentNode())
         parentNode()->childrenChanged();
 
     return characterLengthLimit;
 }
 
 void CharacterData::appendData(const String& data)
@@ skipping 119 matching lines @@
 {
     return static_cast<int>(length());
 }
 
 bool CharacterData::offsetInCharacters() const
 {
     return true;
 }
 
 } // namespace WebCore