To have a better performance would be nice to cancel report rendering automatically or manually. If I am asking for a big report and after I change parameters and request new report, the previous request is still in progress and it is not going to be cancelled. Therefore I see high memory consumption on continuously refreshing a reports with a big data and after some time I see complete slow down of the Reporting Service and of course slow down of the server itself. The memory in this case is not released and Reporting Service crashes sometimes.