gh-150942: Optimize :func:re.split performance by using reference-stealing list append

Author: snurf198

Misc/NEWS.d/next/Library/2026-08-17-14-49-02.gh-issue-150942.y1jM9t.rst

@@ -0,0 +1,3 @@
+Speed up :func:`re.split` by appending result items to the output list
+without an extra reference-count round-trip (using the internal
+reference-stealing list append helper).

Modules/_sre/sre.c

@@ -1273,8 +1273,7 @@ _sre_SRE_Pattern_split_impl(PatternObject *self, PyObject *string,
             );
         if (!item)
             goto error;
-        status = PyList_Append(list, item);
-        Py_DECREF(item);
+        status = _PyList_AppendTakeRef((PyListObject *)list, item);
         if (status < 0)
             goto error;
 
@@ -1283,8 +1282,7 @@ _sre_SRE_Pattern_split_impl(PatternObject *self, PyObject *string,
             item = state_getslice(&state, i+1, string, 0);
             if (!item)
                 goto error;
-            status = PyList_Append(list, item);
-            Py_DECREF(item);
+            status = _PyList_AppendTakeRef((PyListObject *)list, item);
             if (status < 0)
                 goto error;
         }
@@ -1301,8 +1299,7 @@ _sre_SRE_Pattern_split_impl(PatternObject *self, PyObject *string,
         );
     if (!item)
         goto error;
-    status = PyList_Append(list, item);
-    Py_DECREF(item);
+    status = _PyList_AppendTakeRef((PyListObject *)list, item);
     if (status < 0)
         goto error;