From XML inside CLOB, to Oracle table with list of paths

In a previous question, I've asked how to transform a clob into a table, see this:

From XML to list of paths in Oracle PL/SQL environment

The answer I received was great, and it works for XML not too big.

But if I have a table called MY_TABLE_ONE with a field called MY_FIELD which is a CLOB with a very large content (for example 500 Kbytes), the following statement WON'T exit in a reasonable time:

CREATE TABLE MY_TABLE_TWO
AS
   WITH PARAMS AS (SELECT   XMLTYPE (MY_FIELD) FROM MY_TABLE_ONE)
   SELECT   ELEMENT_PATH, ELEMENT_TEXT
     FROM   XMLTABLE (
               '              
      for $i in $doc/descendant-or-self::*
        return <element>
                 <element_path> {$i/string-join(ancestor-or-self::*/name(.), ''/'')} </element_path>
                 <element_content> {$i/text()}</element_content>
               </element>  
    '
                  PASSING (SELECT   * FROM PARAMS) AS "doc"
                  COLUMNS ELEMENT_PATH VARCHAR2 (4000) PATH '//element_path',
                          ELEMENT_TEXT VARCHAR2 (4000) PATH '//element_content'
            );

Is there any alternative way to transform an XML stored inside CLOB column, in an Oracle table with the list of the paths and the respective values, in a more EFFICIENT way?

The above statement is right, but it needs too much time to finalize.

Thank you very much for considering my request.