Improving the execution time of a report in Reporting Services.

In Reporting Services Designer every time you make a change in the design window, and then preview it, it re-executes the query or stored procedure you are reporting against. If you are unable to narrow the selection criteria this can impose serious time constraints on report design, even if you make a minor modification to, say, a column sizing, on preview the SP/Query will re-execute before you can preview the change. This has crippled the speed at which I have been working on these reports.

Caching has been added to preview in Report Designer. When a report is previewed, the data for the report is stored in a file on the local computer. When the same report is previewed again with the same query, parameters, and credentials, Report Designer uses the cache file instead of rerunning the queries in the report. This increases performance of preview in Report Designer.
The data file is saved with the following filename: reportname.rdl.data. The file is located in the same directory as the RDL file. The file is not deleted when Report Designer is closed.

Use the following example to guide you in adding these settings to your configuration file [RSReportDesigner.config]. The new setting is in bold.

<Configuration>
<Add Key="SecureConnectionLevel" Value="0" />
<Add Key="InstanceName" Value="Microsoft.ReportingServices.PreviewServer" />
<Add Key="SessionCookies" Value="true" />
<Add Key="SessionTimeoutMinutes" Value="3" />
<Add Key="PolicyLevel" Value="rspreviewpolicy.config" />
<Add Key="CacheDataForPreview" Value="true" />
<Extensions>
...
</Extensions>
</Configuration>

Usually found at:
C:\Program Files\Microsoft SQL Server\80\Tools\Report Designer\RSReportDesigner.config

I cannot describe how much this speeds up the report design process.