Issues while generating reports in report studio...

[vignesvar]

Hi experts,
I'm using report studio 10.2 to generate reports using Dimensional package. Here I'm having a small problem that is when I add total from summarize menu take too long time to generate report. When I removed that total from table design getting result quickly. I'm using date prompt to filter the data. Reports generate very slow on first time to select the date in prompt again I select the same date getting faster than previous time.
Please let me why it is happening.

Thank you in advance.

Have a nice day