I have a report that includes several row groups on a tablix.
When running this report from Report Manager within Internet Explorer 8.0 the report takes seconds to render to the user (around 7 seconds in one particular test case).
When running this same report with the same parameters within Internet Explorer 8.0 but using the ReportViewer.aspx URL (i.e. via http://server/ReportServer/pages/ReportViewer.aspx?... ) the report takes over 1 minute to render!
We need to be able to call up this report via ReportViewer.aspx because the report call (and relative parameters) are passed to the URL from an application. Currently this performance discrepancy is a showstopper for us.