diff -urp Python-2.7.5.orig/Python/bltinmodule.c Python-2.7.5/Python/bltinmodule.c
--- Python-2.7.5.orig/Python/bltinmodule.c	2013-05-12 06:32:53.000000000 +0300
+++ Python-2.7.5/Python/bltinmodule.c	2013-07-04 10:38:53.000000000 +0300
@@ -2399,6 +2392,65 @@ builtin_sum(PyObject *self, PyObject *ar
             }
         }
     }
+
+    if (PyList_CheckExact(result) || PyTuple_CheckExact(result)) {
+        PyTypeObject *optimized_for = Py_TYPE(result);
+        PyObject *l_result = PyList_New(0);
+        if (l_result == NULL) {
+            Py_DECREF(result);
+            Py_DECREF(iter);
+            return NULL;
+        }
+        temp = _PyList_Extend((PyListObject*)l_result, result);
+        Py_DECREF(result);
+        result = NULL;
+        if (temp == NULL) {
+            Py_DECREF(l_result);
+            Py_DECREF(iter);
+            return NULL;
+        }
+        Py_DECREF(temp);
+        for (;;) {
+            item = PyIter_Next(iter);
+            if (item == NULL) {
+                if (PyErr_Occurred()) {
+                    Py_DECREF(l_result);
+                    return NULL;
+                }
+                break;
+            }
+            if (Py_TYPE(item) != optimized_for)
+                break;
+            temp = _PyList_Extend((PyListObject*)l_result, item);
+            if (temp == NULL)
+                break;
+            Py_DECREF(item);
+            Py_DECREF(temp);
+        }
+        /* Different class, could not extend, or end of sequence. Restore real objects ... */
+        if (optimized_for == &PyList_Type)
+            result = l_result;
+        else /* optimized_for == &PyTuple_Type */ {
+            result = PyList_AsTuple(l_result);
+            Py_DECREF(l_result);
+            if (result == NULL) {
+                Py_DECREF(item);
+                Py_DECREF(iter);
+                return NULL;
+            }
+        }
+        /* ... and process normally */
+        if (item != NULL) {
+            temp = PyNumber_Add(result, item);
+            Py_DECREF(result);
+            Py_DECREF(item);
+            result = temp;
+            if (result == NULL) {
+                Py_DECREF(iter);
+                return NULL;
+            }
+        }
+    }
 #endif
 
     for(;;) {