Explanation/Reference:
Explanation:
http://technet.microsoft.com/en-us/library/bb522786.aspx
Performance, Snapshots, Caching (Reporting Services)
If a single report is processingslowly, tune report dataset queries if the report must run on demand. You might also consider using shared datasets that you can cache, caching the report, or running the report as a snapshot.
Note: Caching Reports (SSRS)
A report server can cache a copy of a processed report and return that copy when a user opens the report.
To a user, the only evidence available to indicate the report is a cached copy is the date and time that the report ran. If the date or time is not current and the report is not a snapshot, the report was retrieved from cache. Caching can shorten the time required to retrieve a report if the report is large or accessed frequently. If the server is rebooted, all cached instances are reinstated when the Report Server Web service comes back online.
Caching is aperformance-enhancement technique. The contents of the cache are volatile and can change as reports are added, replaced, or removed.