First of all, you should indeed follow Adhiyan's advice:
In parallel, you should try to optimize the report queries: most of time, it is a question of too much complex groups in the page activity/list table, and often resolved by doing some groups/count by in the Query activity instead.
Alternative, when this is not a question of count/group by but more a question of lines count : restricting result set to a medium value, if possible for you.
But of course, it depends on each use case. So please may you share more information about your page report/underlying SQL query?