Slicers are a fairly new feature, part of the Dashboard feature. They let the user make selections.
For example, a dashboard could start off showing data for multiple regions and the user can use a slicer to pick a particular region to limit the dashboard to that region.
To come up with the list of regions, the slicer performs a query against the data source. In most cases, this query can be very quick. It selects the distinct list of values for region in the table. In some cases, however, finding all the regions in a large table that is not indexes by region could be time consuming causing delay in loading the dashboard.
Performance could be greatly improved if we get the list of regions directly from a “region” table. Often such a table exists that has the data that we need for the slicer choices.
I hope you find this tip useful!