Could you please tune this statement to save time 50% off?

The statement shown below takes 50 min. when I query  sys.aud$  table, consist of 5.6 mil records by log keeper application.

The purpose is to get all information from sys.aud$ and then create the reports.

I belive that the statement may not be tuned. Please help me to save my time.

I use Oracle 10.1.0.5 Enterprise Edition.

I will try any statement and report you what going on here.

Thanks,

-Red DBA

%TRACKING% =

  SELECT TO_CHAR (MAX (CAST ((FROM_TZ ("SYS"."AUD$"."NTIMESTAMP#", '00:00') AT LOCAL) AS DATE)), 'yyyy-mm-dd hh24:mi:ss')  FROM "SYS"."AUD$";

The outcome of the %TRACKING% above is used in the following statement: