if we run a report it is taking so much time to display the 
result to be fallowed as :

     1) use aggrigate tables(contains pre caliculated data) 
     2)pre defined conditions,LOV's
     3)in a real time senario query contains a large if 
statements.some times we need to wait max of 30 min to run 
perticular statement...not all

If the question is not pertaining to query optimization, I 
would prefer not to use much of formatting on the page. One 
can keep the report without any page formatting as this 
would take a very long time. Try not to use the slice & 
dice panel as this would also take considerably long time...

Remove unnecessary objects and variables if any.make sure 
you remove alerters if any unless it is the 
requirement.Take the report query and run in Database.See 
how much time its taking.From report query check whether 
in 'where' clause columns have indexes.If not discuss with 
oracle admin and add indexes.