Isue #5084: unpickling now interns the attribute names of pickled objects,
saving memory and avoiding growth in size of subsequent pickles. Proposal
and original patch by Jake McGuire.
diff --git a/Lib/pickle.py b/Lib/pickle.py
index abed1ca..8c5d51f 100644
--- a/Lib/pickle.py
+++ b/Lib/pickle.py
@@ -1221,7 +1221,15 @@
             state, slotstate = state
         if state:
             try:
-                inst.__dict__.update(state)
+                d = inst.__dict__
+                try:
+                    for k, v in state.iteritems():
+                        d[intern(k)] = v
+                # keys in state don't have to be strings
+                # don't blow up, but don't go out of our way
+                except TypeError:
+                    d.update(state)
+
             except RuntimeError:
                 # XXX In restricted execution, the instance's __dict__
                 # is not accessible.  Use the old way of unpickling