I have a data driven website that used to depend on the reports module for rendering most of it's content. The site seemed slow and sluggish. When I discovered the cause for the poor performance I was shocked: The view state for each page was hundreds of kilobytes!

It looks that the reports module duplicates the report output in the view state. So if your report generates 100KB of output, another 100KB will be added to the page view state. That is 200KB in total, of which 50% is unnessesary. And another problem with the view state is that it is posted back with all ajax calls and postback links. Effectively making the page unusable.

The report data can be recreated on the server when needed. The reports module has all the information to do so. There is no valid reason for the excessive use of the view state. This is a problem that should be easy to fix in the reports module. I have logged the issue in Gemeni: http://support.dotnetnuke.com/issue/ViewIssue.aspx?id=10555&PROJID=23

In the mean time, my solution was to save the report output xml to disk and replace the reports module with the xml module. The size of the view state was reduced by approx 95%. Now, my site is fast and slick!