UI Virtualization
RadGridView's API supports UI Virtualization which processes only these visual elements that are loaded in its viewable area. This reduces the memory footprint of the application and speeds up the loading time, thus immensely enhancing the UI performance.
The grid control utilizes horizontal and vertical virtualization and introduces container recycling for speed improvement and reduction in memory usage. This is of great importance when the control is bound to large data sets. The container recycling pushes further the speed of horizontal and vertical scrolling, allowing RadGridView to reuse the existing containers for the different data items from the source collection instead of creating new ones.
You should not work with the visual elements of RadGridView(GridViewCell, GridViewRow, etc.) directly as this will result in inconsistent behavior due to the containers recycling mechanism. Instead, you should use the underlying data items as explained in the Style Selectors section.
These techniques, combined with the outstanding LINQ-based data engine, guarantee fast performance.
Both EnableColumnVirtualization and EnableRowVirtualization properties of RadGridView are set to True by default.
In case the UI Virtualization is disabled, then all the visual elements will be loaded once RadGridView is visualized and its items are populated. This can lead to huge performance issues and additional loading time. Disabling the virtualization is highly not recommended.
Do not place RadGridView in controls/panels which will measure it with infinity as this will disable the UI Virtualization. For example, ScrollViewer, StackPanel and Grid with Row.Height=Auto or Column.Width=Auto will measure it in that way. You can place it in RowDefinition with Height="*" instead.
You can check the topic on Styling or content mixed-up on scrolling on some issues with styling the visual elements.