Using SSRS in SharePoint mode version 2008 R2 or earlier full-page report rendering is slower than its corresponding Native mode. This is largely due to SSRS in SharePoint mode comprises Native mode functionality and additional calls to the SharePoint object model APIs for SharePoint integration specific operations. Additionally, for some reports with short Native mode rendering times especially those less than 500ms or 1s can be found to be 2-3 times slower in SharePoint mode when compared to a typical Native mode SSRS install. This can also be inferred / approximated from the "First Page Report Performance" graph in the Reporting Services Performance in SharePoint Integrated Mode in SQL Server 2008 R2.
In the SQL Server Denali CTP3 of SSRS Reporting Services for SharePoint 2010 we have improved our integration with SharePoint 2010 which truly improves performance. This entailed changes and optimizations for the end-to-end full-page report viewing / rendering scenario starting with the SSRS Report Viewer SharePoint web part’s behavior such as in its toolbar, followed by communication between the web part and the back end server, and the interaction between SSRS components and SharePoint itself. As a result of this, in SharePoint mode full-page report rendering is either at par if not very close at par (differ by fractions of a second) with Native mode.
Hence, how do you get this performance improvement?
Visit the SQL Server Code name Denali CTP3 site and to download. Send feedback via http://connect.microsoft.com as well.