diff --git a/CHANGES.txt b/CHANGES.txt
index 7079ef0..cd53525 100644
--- a/CHANGES.txt
+++ b/CHANGES.txt
@@ -14,6 +14,11 @@ Changelog
   Related to https://dev.plone.org/plone/ticket/11737
   [WouterVH]
 
+- Do not render/update the comment form in CommentViewlets if commenting is
+  disabled, since this slows down the page rendering. This fixes
+  http://dev.plone.org/plone/ticket/11930
+  [fafhrd]
+
 
 2.0.4 (2011-05-28)
 ------------------
diff --git a/plone/app/discussion/browser/comments.py b/plone/app/discussion/browser/comments.py
index d9f0431..159d3af 100644
--- a/plone/app/discussion/browser/comments.py
+++ b/plone/app/discussion/browser/comments.py
@@ -248,10 +248,13 @@ class CommentsViewlet(ViewletBase):
 
     def update(self):
         super(CommentsViewlet, self).update()
-        z2.switch_on(self, request_layer=IFormLayer)
-        self.form = self.form(aq_inner(self.context), self.request)
-        alsoProvides(self.form, IWrappedForm)
-        self.form.update()
+        if self.is_discussion_allowed() and \
+           (self.is_anonymous() and self.anonymous_discussion_allowed() \
+            or self.can_reply()):
+            z2.switch_on(self, request_layer=IFormLayer)
+            self.form = self.form(aq_inner(self.context), self.request)
+            alsoProvides(self.form, IWrappedForm)
+            self.form.update()
 
     # view methods