In short, give away the work of db to itself. ‘Push down strategy’!
If you could accomplish a task in universe which you right now do it in your report, choose the way of doing it in universe itself.
Delete all the unused variables and formulas in the report.
Restrict the data at the data provider itself, instead of bringing it and filtering at the report level using filters.
Check this topic.
Most importantly check this FAQ.
Jansi 
(BOB member since 2008-05-12)