When you use excel as a data source, you have a few options on how that excel data is stored and accessed. This video tip covers keeping data cached in Dundas BI, how to allow for real-time access or how to allow for semi-realtime access with warehousing.
You might also enjoy this video covering a common issue that people may see with data performance when using a Dundas Data Cube to create a data warehouse.
If you’d like to learn more, I’d recommend you go to my learning channel - Off the Charts (with Jeff).
https://www.dundas.com/resources/off-the-charts-tips-from-an-expert