Scenario: when the client runs the reports on 3 different screens. And it takes too long for these reports to be generated. Also, they encounter an error message. 
Reasons:
- You cannot run more than two different reports at one time. If you attempt to run a third report when two reports are already running, you receive an error. You can wait until another report is finished, or cancel another report, then try again. Or, for some reports, you can save the report, then schedule it to be run and its results to be emailed to you later.
- You cannot run more than one instance of the same report at one time. Generally, if you rerun a report that is already running, the first instance is canceled, and the second instance is run. Note that if you send duplicate requests to run the same report within a short period of time, you will receive a message telling you to wait until the first report execution is complete.
- For long-running reports, usually those with a large amount of data, a popup option lets you run the report in the background and be alerted when the report is completed. You also have the option of scheduling reports to run at specific times.
- Warning: After you have started running a report, do not start other reports until the first one is complete. Executing multiple reports at the same time can cause significant performance issues. If a report is slow, it is best to schedule it, if possible.
- When a report’s running time is lengthy, a message appears as the report is running on your desktop and you are given the option to click Alert me when ready. The report then runs in the background and you receive an email when the report is completed, with a link to its results.