diff --git a/Objects/listobject.c b/Objects/listobject.c
index 47673be..66e4460 100644
--- a/Objects/listobject.c
+++ b/Objects/listobject.c
@@ -2234,6 +2234,13 @@
 	return PyObject_RichCompare(vl->ob_item[i], wl->ob_item[i], op);
 }
 
+/* empirically determined threshold for activating an optimisation
+ * in list_fill() - 100 seems close to optimum for current CPUs and
+ * compilers, as of December '03.
+ * see also comment in list_fill().
+ */
+#define	LISTFILL_OPT_THRESHOLD	100
+
 /* Adapted from newer code by Tim */
 static int
 list_fill(PyListObject *result, PyObject *v)
@@ -2242,14 +2249,29 @@
 	int n;		   /* guess for result list size */
 	int i;
 
+	/* if source is destination, we're done. */
+	if (v == (PyObject *)result)
+		return 0;
+
 	n = result->ob_size;
 
-	/* Special-case list(a_list), for speed. */
-	if (PyList_Check(v)) {
-		if (v == (PyObject *)result)
-			return 0; /* source is destination, we're done */
-		return list_ass_slice(result, 0, n, v);
-	}
+	/* Special-case list(a_list), for speed:
+	 * - if the source has 0 elements, there's nothing to copy.
+	 * - if the source has more than a threshold number of elements
+	 *   slice assignment is a faster way of filling the target
+	 *   (the exact threshold is subject to empirical determination).
+	 * Also special case any other zero length sequence, including
+	 * subclasses of list, there being nothing to copy.
+	 */
+	if (PyList_CheckExact(v)) {
+		i = ((PyListObject*)v)->ob_size;
+		if (i == 0)
+			return 0;
+		if (i > LISTFILL_OPT_THRESHOLD)
+			return list_ass_slice(result, 0, n, v);
+	} else
+		if (PySequence_Check(v) && PySequence_Size(v) == 0)
+			return 0;
 
 	/* Empty previous contents */
 	if (n != 0) {