diff --git a/Lib/pickle.py b/Lib/pickle.py
index b812e675c5a..cb27f8ab859 100644
--- a/Lib/pickle.py
+++ b/Lib/pickle.py
@@ -45,6 +45,9 @@
                       "2.0",            # Protocol 2
                       ]                 # Old format versions we can read
 
+# Why use struct.pack() for pickling but marshal.loads() for
+# unpickling?  struct.pack() is 40% faster than marshal.loads(), but
+# marshal.loads() is twice as fast as struct.unpack()!
 mloads = marshal.loads
 
 class PickleError(Exception):