Tune query

Hi,

Please help me tune below query.

SELECT me.vac_ref, me.job_title, me.location, me.email FROM (SELECT me.vac_ref, me.job_title, me.location, me.email  FROM VACANCY me  ORDER BY vac_ref ASC) me WHERE ROWNUM <= :rowcount;

Explain Plan output
-------------------
--------------------------------------------------------------------------------
| Id  | Operation               | Name    | Rows  | Bytes |TempSpc| Cost (%CPU)|
--------------------------------------------------------------------------------
|   0 | SELECT STATEMENT        |         |    21M|  4489M|       |  2129K  (1)|
|   1 |  COUNT STOPKEY          |         |       |       |       |            |
|   2 |   VIEW                  |         |    21M|  4489M|       |  2129K  (1)|
|   3 |    SORT ORDER BY STOPKEY|         |    21M|  1848M|  4267M|  2129K  (1)|
|   4 |     TABLE ACCESS FULL   | VACANCY |    21M|  1848M|       |  1682K  (1)|
--------------------------------------------------------------------------------

Regards
Raj