* Replace PyArg_ParseTupleAndKeywords() with _PyArg_ParseStackAndKeywords()
  which is more efficient to parse keywords, since it decodes only keywords
  (char*) from UTF-8 once, instead of decoding at each call.
* METH_FASTCALL avoids the creation of a temporary tuple to pass positional
  arguments.

Patch written by INADA Naoki, pushed by Victor Stinner.