bpo-43464: Optimize set.intersection() for non-set arguments (GH-31316)

Author: serhiy-storchaka

Misc/NEWS.d/next/Core and Builtins/2022-02-13-21-53-29.bpo-43464.yupHjd.rst

@@ -0,0 +1 @@
+Optimize :meth:`set.intersection` for non-set arguments.

Objects/setobject.c

@@ -1240,6 +1240,10 @@ set_intersection(PySetObject *so, PyObject *other)
         if (rv) {
             if (set_add_entry(result, key, hash))
                 goto error;
+            if (PySet_GET_SIZE(result) >= PySet_GET_SIZE(so)) {
+                Py_DECREF(key);
+                break;
+            }
         }
         Py_DECREF(key);
     }