We tend to get an issue in the ASP.NET support group from time to time that is around Reporting Services. These are generally issues around the process taking up large amounts of memory or slow performance or similar things. Generally the reason behind this is due to the way the reports have been configured. For example, trying to pull down a 1,000 page report.
We now have some very good documentation on some best practices around how to properly use Reporting Services. You can read all about it from these links:
Hope that you get everything you want out of your reports in the future with no problems.