SQL> create table xtest as
  2  select a as v
  3        ,xmltype(a) as x
  4        ,to_clob(a) as c
  5  from (select '<a>'||lpad(1,3900,1)||'</a>' a from dual connect by level<=1000);

Table created.

SQL> set arrays 1000;
SQL> set autot trace stat;
SQL> select v,v,v from xtest;

1000 rows selected.


Statistics
----------------------------------------------------------
          7  recursive calls
          0  db block gets
       1068  consistent gets
       1000  physical reads
          0  redo size
      29001  bytes sent via SQL*Net to client
        360  bytes received via SQL*Net from client
          2  SQL*Net roundtrips to/from client
          0  sorts (memory)
          0  sorts (disk)
       1000  rows processed

SQL> select x,x,x from xtest;

1000 rows selected.


Statistics
----------------------------------------------------------
        377  recursive calls
          0  db block gets
       5083  consistent gets
         31  physical reads
          0  redo size
   12731016  bytes sent via SQL*Net to client
     427179  bytes received via SQL*Net from client
       3009  SQL*Net roundtrips to/from client
          2  sorts (memory)
          0  sorts (disk)
       1000  rows processed

SQL> select c,c,c from xtest;

1000 rows selected.


Statistics
----------------------------------------------------------
          5  recursive calls
          0  db block gets
       4066  consistent gets
       3000  physical reads
          0  redo size
   24494417  bytes sent via SQL*Net to client
     500360  bytes received via SQL*Net from client
       4002  SQL*Net roundtrips to/from client
          0  sorts (memory)
          0  sorts (disk)
       1000  rows processed

SQL> set autot off;