I have a problem in SQL Server 2008 Reporting Services. The problem is that the report is sometimes too slow to render (it takes more than 30 min), although I took the query and executed it in SQL Server Management Studio and it didn't take more than 25 seconds.
The query returns a large table (about 5000 rows) and I use it to draw a pie chart in the report, I tried to optimize the query so that it returns only 4 rows but the report was slow again.
What confuses me is that sometimes the report (with different input) is as fast as the query (about 30 sec), I thought it might be because of low number of users so I tried with some colleagues to view it at the same time but the reports still are fast, I tried to change in the configuration but I had no luck.
I've been searching for a solution for this problem for more than two months, so if anyone could help me on this I will be very thankful.