From d33e6be59df8cd8ba701d744ffc2fc7e2d483daa Mon Sep 17 00:00:00 2001
From: Tim Peters <tim.peters@gmail.com>
Date: Sun, 25 Aug 2002 19:12:45 +0000
Subject: [PATCH] Sped intersection by large factors (3-5x faster than before
 on sets of cardinality 500; and the smaller the intersection, the bigger the
 speedup).

---
 Lib/sets.py | 9 ++-------
 1 file changed, 2 insertions(+), 7 deletions(-)

diff --git a/Lib/sets.py b/Lib/sets.py
index 8808701d244..e88e845c1fd 100644
--- a/Lib/sets.py
+++ b/Lib/sets.py
@@ -176,13 +176,8 @@ class BaseSet(object):
             little, big = self, other
         else:
             little, big = other, self
-        result = self.__class__()
-        data = result._data
-        value = True
-        for elt in little:
-            if elt in big:
-                data[elt] = value
-        return result
+        common = filter(big._data.has_key, little._data.iterkeys())
+        return self.__class__(common)
 
     def intersection(self, other):
         """Return the intersection of two sets as a new set.