Index: Lib/heapq.py
===================================================================
--- Lib/heapq.py	(revision 67989)
+++ Lib/heapq.py	(working copy)
@@ -354,6 +354,8 @@
 
     Equivalent to:  sorted(iterable, key=key)[:n]
     """
+    if key is None:
+        return _nsmallest(n, iterable)
     in1, in2 = tee(iterable)
     keys = in1 if key is None else map(key, in1)
     it = zip(keys, count(), in2)                           # decorate
@@ -366,6 +368,8 @@
 
     Equivalent to:  sorted(iterable, key=key, reverse=True)[:n]
     """
+    if key is None:
+        return _nlargest(n, iterable)
     in1, in2 = tee(iterable)
     keys = in1 if key is None else map(key, in1)
     it = zip(keys, map(neg, count()), in2)                 # decorate