Hi,
Just another couple of tips:
Keep the report (and the query) as lean as possible - ie don't bring in items that are not required.
Try to keep the number of items you group and/or sort on to a minimum - ie use 'level span' where appropriate rather than grouping on a second column having a 1:1 relationship with an existing grouped column.
Try to keep the number of query calculations to a minimum, and particularly try to avoid using functions/summaries that you know may give poor performance.
Regards,
MF.