In a generic value report tuning is to give a final touch 
to the report before putting it to production server.

Are you asking Business Objects reports tuning, if "Yes" 
then, the answer is 

- By reducing the number of variables
- By reducing the number of Data providers
- By pulling the exact amount of the data from the database
- By reducing the complex variables
- Do not check the "Refresh on open " report.

these are the some of the possible ways of tuning the 
reports.

To add some with the before answers

Avoid Using objects from dreived tables.

Reduce the joins in the query.

Create index in the database level.

Apply the filter Properly as per the logic