Restrict Content Loading to the Visible Area of the Screen
Viewport Loading improves the performance of SAP Analytics Cloud by only loading the content that is in the visible area of the screen.
You can speed up story performance by choosing to only load the objects in the viewport area. Instead of waiting for all of the objects in your story to load, you can start interacting with the data right away.
Other objects will be installed when you scroll to a new section, but not until you stop scrolling.
Note
Viewport loading is only available when your story has optimized view mode enabled. For more information, see Enabling Optimized View Mode.
To use the viewport loading feature, from the toolbar select 
Data Refresh 
Enable Viewport Loading
.