There is few factors which will case performance like ;

 

 

Special Fields : PageNofM

 

If you place your sub report in a repeted sections like 'Groups / Detaile.  Please remove your sub report from group or detail and place it either Report header / Report footer -- this will be executed only once.

 

or

 

If you are linking more tables, shift to Add Command which will be executed fast and also if you have any report level parameters try to create at Command level this will filter the data and get the required data into your report.

 

or

 

If you are using any Dynamic Parameters, try to create a Business View and create List of Values at Business View end and schedule it, this will reduce the time of getting list of values when you refresh your report.

 

or

 

Try to avoid running totals if any