This is the fastest I could get on Intel GCC. I kept the memset() in to clear

the newly created tuples, but tuples added in the freelist are now cleared in
tupledealloc already (which is very cheap, because we are already
Py_XDECREF'ing all elements anyway).

Python should have a standard Py_ZAP macro like ZAP in pystate.c.

Objects/tupleobject.c

@@ -68,9 +68,8 @@ PyTuple_New(register int size)
 		op = PyObject_GC_NewVar(PyTupleObject, &PyTuple_Type, size);
 		if (op == NULL)
 			return NULL;
+		memset(op->ob_item, 0, size*sizeof(PyObject*));
 	}
-	for (i=0; i < size; i++)
-		op->ob_item[i] = NULL;
 #if MAXSAVESIZE > 0
 	if (size == 0) {
 		free_tuples[0] = op;
@@ -165,19 +164,27 @@ tupledealloc(register PyTupleObject *op)
 	Py_TRASHCAN_SAFE_BEGIN(op)
 	if (len > 0) {
 		i = len;
-		while (--i >= 0)
-			Py_XDECREF(op->ob_item[i]);
 #if MAXSAVESIZE > 0
 		if (len < MAXSAVESIZE &&
 		    num_free_tuples[len] < MAXSAVEDTUPLES &&
 		    op->ob_type == &PyTuple_Type)
 		{
+			while (--i >= 0) {
+				PyObject* o = op->ob_item[i];
+				if (o != NULL) {
+					op->ob_item[i] = NULL;
+					Py_DECREF(o);
+				}
+			}
 			op->ob_item[0] = (PyObject *) free_tuples[len];
 			num_free_tuples[len]++;
 			free_tuples[len] = op;
 			goto done; /* return */
 		}
+		else
 #endif
+			while (--i >= 0)
+				Py_XDECREF(op->ob_item[i]);
 	}
 	op->ob_type->tp_free((PyObject *)op);
 done: