diff --git a/Lib/functools.py b/Lib/functools.py
index 89f2cf4..0873f20 100644
--- a/Lib/functools.py
+++ b/Lib/functools.py
@@ -432,6 +432,10 @@
     saves space and improves lookup speed.
 
     """
+    # All of code below relies on kwds preserving the order input by the user.
+    # Formerly, we sorted() the kwds before looping.  The new way is *much*
+    # faster; however, it means that f(x=1, y=2) will now be treated as a
+    # distinct call from f(y=2, x=1) which will be cached separately.
     key = args
     if kwds:
         key += kwd_mark