Reports can place a heavy burden on your data sources as well as the report server. In order to mitigate the query load due to reporting, administrators can apply options to cache data as well as an entire rendered report. The two methods that SSRS has to manage caching are:
Report caching uses the same principles as any Web-caching engine, with the exception that caching only applies to data. When you set up a report to be rendered from a cache, SSRS will cache the data set for the report. Each subsequent execution of the report will not query the data source for the data, but will instead retrieve the data set cached in the ReportServerTempDB database. SSRS then applies the report definition, ...