How to use cache In Dashboard

Hi All

I have Sap BO 4.0 with Support Pack 2

we have 16 dashboards on production server.

but I need to know how should I use this cache concept because

user need if they run that dashboard 20 times a time for next 19 times it should open directly from cache

means it should use cache concept so that it will not take much run time.

so I need to know how should I use this Cache concept..

Regards,

Sagar.