We are running IIS & SSRS on the same production server and have two types of reports - one running through Report Viewer, connecting to SSRS (remote mode) and the other calling the SSRS web service to generate PDFs.
For both of the report types, it becomes very slow when loading the page, taking upwards of 20 seconds. It is most evident during periods of heavy server load and the slowness will go away after recycling the application pool in IIS but comes back after a while (the application pool is set to recycle daily at 3am).
I have checked the execution log of SSRS - for all the reports the time for data retrieval + processing + rendering will take no more than 2 seconds and the http logs of SSRS indicate that there is no request from IIS when the page becomes unresponsive - once the request does reach it loads very quickly. The reports when run through the report manager are very fast also.
It does not seem like SSRS is the culprit here and seems like something in IIS is causing it.
Has anyone else encountered a similar problem or can point me in the right direction for diagnosing?