Sql performance

Hi,

There is one report running using with clause where sys_temp is being used and selecting 12G.  How to tune this plan ? Any idea?

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| Id  | Operation                                                  | Name                           | Rows  | Bytes |TempSpc| Cost (%CPU)| Time     |

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|   0 | SELECT STATEMENT                                           |                                |  1644K|    12G|       |  9513K  (1)| 00:06:12 |

|   1 |  TEMP TABLE TRANSFORMATION                                 |                                |       |       |       |            |          |

|   2 |   LOAD AS SELECT                                           | SYS_TEMP_0FD9E2286_76094D34    |       |       |       |            |          |

|*  3 |    TABLE ACCESS BY INDEX ROWID BATCHED                     | Table                 |    11M|  1506M|       |   347K  (1)| 00:00:14 |

|*  4 |     INDEX RANGE SCAN                                       | Index   |    13M|       |       |  7056   (1)| 00:00:01 |

|   5 |   LOAD AS SELECT                                           | SYS_TEMP_0FD9E2287_76094D34    |       |       |       |            |          |

|   6 |    HASH UNIQUE                                             |                                |  1110K|    25M|   395M|   199K  (1)| 00:00:08 |

|*  7 |     VIEW                                                   |                                |    11M|   261M|       |   166K  (1)| 00:00:07 |