How practical is it to consider SSRS 2005 or SSRS 2008 as a reporting solution for a report that has to show reports with millions of records (records vary from 3 to 10 million)? Is there any threshold on the size of report in SSRS?

How do I know that for a huge report, wheather SSRS will consume the whole memory and start paging the operations to disk or it will give a memory leak error? Even if I keep on increasing the memory how can I be sure that certain memory will be sufficient for such huge reports for the report server?

All the above questions are haunting me because I have a dedicated report server with a decent hardware and OS configuration (8 processors, 8GB RAM, 64 bit OS and 64 bit SQL Server 2005). Still my report with around 2 million records is taking more than 6 minutes and going from one page to another takes 3 minutes!!!

My datasource is on separate server and when I execute only the stored proc there, it returns the results in less than 2 minutes.