Inada's patch version act different inside `PyObject_SetItem`, 

when running this code: 'x = {}; x['a'] = 123'

at PyObject_SetItem,

patch version goes to this line:
  >│179         if (m && m->mp_ass_subscript)
   │180             return m->mp_ass_subscript(o, key, value);

but original version goes to:
  >│182         if (o->ob_type->tp_as_sequence) {
   │183             if (PyIndex_Check(key)) {

I think that's why the performance issue came out, still digging why this happened.