diff --git a/ietf/doc/migrations/0016_move_dochistory.py b/ietf/doc/migrations/0016_move_dochistory.py
index 3a43edb3b..cfc98529b 100644
--- a/ietf/doc/migrations/0016_move_dochistory.py
+++ b/ietf/doc/migrations/0016_move_dochistory.py
@@ -25,14 +25,10 @@ def forward(apps, schema_editor):
     ).exists()
 
 
-def reverse(apps, schema_editor):
-    # there is no going back
-    raise NotImplementedError
-
-
 class Migration(migrations.Migration):
     dependencies = [
         ("doc", "0015_delete_docalias"),
     ]
 
-    operations = [migrations.RunPython(forward, reverse)]
+    # There is no going back
+    operations = [migrations.RunPython(forward)]
diff --git a/ietf/doc/models.py b/ietf/doc/models.py
index ebc0a575e..075a34753 100644
--- a/ietf/doc/models.py
+++ b/ietf/doc/models.py
@@ -666,13 +666,16 @@ class DocumentInfo(models.Model):
         )
 
     def became_rfc(self):
-        doc = self if isinstance(self, Document) else self.doc
-        return next(iter(doc.related_that_doc("became_rfc")), None)
+        if not hasattr(self, "_cached_became_rfc"):
+            doc = self if isinstance(self, Document) else self.doc
+            self._cached_became_rfc = next(iter(doc.related_that_doc("became_rfc")), None)
+        return self._cached_became_rfc
 
     def came_from_draft(self):
-        doc = self if isinstance(self, Document) else self.doc
-        return next(iter(doc.related_that("became_rfc")), None)
-
+        if not hasattr(self, "_cached_came_from_draft"):
+            doc = self if isinstance(self, Document) else self.doc
+            self.cached_came_from_draft = next(iter(doc.related_that("became_rfc")), None)
+        return self._cached_came_from_draft
 
     class Meta:
         abstract = True
diff --git a/ietf/doc/views_doc.py b/ietf/doc/views_doc.py
index 0c2a65650..c5b4e1296 100644
--- a/ietf/doc/views_doc.py
+++ b/ietf/doc/views_doc.py
@@ -195,6 +195,8 @@ def document_main(request, name, rev=None, document_html=False):
 
     doc = get_object_or_404(Document.objects.select_related(), name=name)
 
+    log.assertion('doc.type_id!="rfc" or doc.name.startswith("rfc")')
+
     # take care of possible redirections
     if document_html is False and rev is None:
         became_rfc = doc.became_rfc()
@@ -1126,8 +1128,10 @@ def document_email(request,name):
 
 
 def get_diff_revisions(request, name, doc):
-    """ returns list of (name, rev, time, url, is_this_doc, is_previous_doc)
-        ordered by -time for use by forms used to get to the diff tools.
+    """ Calculate what to offer for diff comparisons
+    
+    returns list of (name, rev, time, url, is_this_doc, is_previous_doc)
+    ordered by -time for use by forms used to get to the diff tools.
     """
     diffable = any(
         [