diff -r 8545624309f5 Objects/listobject.c
--- a/Objects/listobject.c	Wed Feb 25 20:48:01 2015 -0800
+++ b/Objects/listobject.c	Thu Feb 26 12:40:08 2015 +0200
@@ -1956,6 +1956,7 @@ listsort(PyListObject *self, PyObject *a
         lo.values = NULL;
     }
     else {
+        PyObject *argtuple = NULL;
         if (saved_ob_size < MERGESTATE_TEMP_SIZE/2)
             /* Leverage stack space we allocated but won't otherwise use */
             keys = &ms.temparray[saved_ob_size+1];
@@ -1966,16 +1967,41 @@ listsort(PyListObject *self, PyObject *a
         }
 
         for (i = 0; i < saved_ob_size ; i++) {
-            keys[i] = PyObject_CallFunctionObjArgs(keyfunc, saved_ob_item[i],
-                                                   NULL);
+            if (argtuple == NULL) {
+                argtuple = PyTuple_New(1);
+                if (argtuple == NULL) {
+                    goto cleanup;
+                }
+                Py_INCREF(argtuple);
+            }
+            assert(Py_REFCNT(argtuple) == 2);
+            assert(Py_SIZE(argtuple) == 1);
+            assert(PyTuple_GET_ITEM(argtuple, 0) == NULL);
+            Py_INCREF(saved_ob_item[i]);
+            PyTuple_SET_ITEM(argtuple, 0, saved_ob_item[i]);
+            keys[i] = PyObject_Call(keyfunc, argtuple, NULL);
+            if (Py_REFCNT(argtuple) == 2) {
+                PyTuple_SET_ITEM(argtuple, 0, NULL);
+                Py_DECREF(saved_ob_item[i]);
+            }
+            else {
+                Py_DECREF(argtuple);
+                Py_DECREF(argtuple);
+                argtuple = NULL;
+            }
             if (keys[i] == NULL) {
+cleanup:
                 for (i=i-1 ; i>=0 ; i--)
                     Py_DECREF(keys[i]);
                 if (saved_ob_size >= MERGESTATE_TEMP_SIZE/2)
                     PyMem_FREE(keys);
+                Py_XDECREF(argtuple);
+                Py_XDECREF(argtuple);
                 goto keyfunc_fail;
             }
         }
+        Py_XDECREF(argtuple);
+        Py_XDECREF(argtuple);
 
         lo.keys = keys;
         lo.values = saved_ob_item;
diff -r 8545624309f5 Python/bltinmodule.c
--- a/Python/bltinmodule.c	Wed Feb 25 20:48:01 2015 -0800
+++ b/Python/bltinmodule.c	Thu Feb 26 12:40:08 2015 +0200
@@ -479,6 +479,7 @@ typedef struct {
     PyObject_HEAD
     PyObject *func;
     PyObject *it;
+    PyObject *argtuple;  /* cached args tuple */
 } filterobject;
 
 static PyObject *
@@ -508,6 +509,7 @@ filter_new(PyTypeObject *type, PyObject 
     Py_INCREF(func);
     lz->func = func;
     lz->it = it;
+    lz->argtuple = NULL;
 
     return (PyObject *)lz;
 }
@@ -518,6 +520,8 @@ filter_dealloc(filterobject *lz)
     PyObject_GC_UnTrack(lz);
     Py_XDECREF(lz->func);
     Py_XDECREF(lz->it);
+    Py_XDECREF(lz->argtuple);
+    Py_XDECREF(lz->argtuple);
     Py_TYPE(lz)->tp_free(lz);
 }
 
@@ -547,8 +551,35 @@ filter_next(filterobject *lz)
             ok = PyObject_IsTrue(item);
         } else {
             PyObject *good;
-            good = PyObject_CallFunctionObjArgs(lz->func,
-                                                item, NULL);
+            PyObject *argtuple = lz->argtuple;
+            lz->argtuple = NULL;
+            if (argtuple == NULL) {
+                argtuple = PyTuple_New(1);
+                if (argtuple == NULL) {
+                    Py_DECREF(item);
+                    return NULL;
+                }
+                Py_INCREF(argtuple);
+            }
+            assert(Py_REFCNT(argtuple) == 2);
+            assert(Py_SIZE(argtuple) == 1);
+            assert(PyTuple_GET_ITEM(argtuple, 0) == NULL);
+            PyTuple_SET_ITEM(argtuple, 0, item);
+            good = PyObject_Call(lz->func, argtuple, NULL);
+            if (Py_REFCNT(argtuple) == 2) {
+                PyTuple_SET_ITEM(argtuple, 0, NULL);
+                if (lz->argtuple == NULL)
+                    lz->argtuple = argtuple;
+                else {
+                    Py_DECREF(argtuple);
+                    Py_DECREF(argtuple);
+                }
+            }
+            else {
+                Py_INCREF(item);
+                Py_DECREF(argtuple);
+                Py_DECREF(argtuple);
+            }
             if (good == NULL) {
                 Py_DECREF(item);
                 return NULL;
@@ -1418,6 +1449,7 @@ typedef struct {
     PyObject_HEAD
     PyObject *iters;
     PyObject *func;
+    PyObject *argtuple;  /* cached args tuple */
 } mapobject;
 
 static PyObject *
@@ -1461,6 +1493,7 @@ map_new(PyTypeObject *type, PyObject *ar
     func = PyTuple_GET_ITEM(args, 0);
     Py_INCREF(func);
     lz->func = func;
+    lz->argtuple = NULL;
 
     return (PyObject *)lz;
 }
@@ -1471,6 +1504,8 @@ map_dealloc(mapobject *lz)
     PyObject_GC_UnTrack(lz);
     Py_XDECREF(lz->iters);
     Py_XDECREF(lz->func);
+    Py_XDECREF(lz->argtuple);
+    Py_XDECREF(lz->argtuple);
     Py_TYPE(lz)->tp_free(lz);
 }
 
@@ -1487,23 +1522,47 @@ map_next(mapobject *lz)
 {
     PyObject *val;
     PyObject *argtuple;
-    PyObject *result;
+    PyObject *result = NULL;
     Py_ssize_t numargs, i;
 
+    argtuple = lz->argtuple;
+    lz->argtuple = NULL;
     numargs = PyTuple_Size(lz->iters);
-    argtuple = PyTuple_New(numargs);
-    if (argtuple == NULL)
-        return NULL;
+    if (argtuple == NULL) {
+        argtuple = PyTuple_New(numargs);
+        if (argtuple == NULL)
+            return NULL;
+        Py_INCREF(argtuple);
+    }
+    assert(Py_REFCNT(argtuple) == 2);
+    assert(Py_SIZE(argtuple) == numargs);
+#ifndef NDEBUG
+    for (i = 0; i < numargs; i++)
+        assert(PyTuple_GET_ITEM(argtuple, i) == NULL);
+#endif
 
     for (i=0 ; i<numargs ; i++) {
         val = PyIter_Next(PyTuple_GET_ITEM(lz->iters, i));
         if (val == NULL) {
-            Py_DECREF(argtuple);
-            return NULL;
+            numargs = i;
+            goto cleanup;
         }
         PyTuple_SET_ITEM(argtuple, i, val);
     }
     result = PyObject_Call(lz->func, argtuple, NULL);
+cleanup:
+    if (Py_REFCNT(argtuple) == 2) {
+        for (i = 0; i < numargs; i++) {
+            val = PyTuple_GET_ITEM(argtuple, i);
+            PyTuple_SET_ITEM(argtuple, i, NULL);
+            Py_DECREF(val);
+        }
+        if (lz->argtuple == NULL) {
+            lz->argtuple = argtuple;
+            return result;
+        }
+    }
+    Py_DECREF(argtuple);
     Py_DECREF(argtuple);
     return result;
 }