The performance of the RadGridView scrolling diminishes significantly when the grid has thousands of rows and alternating row styles are used.  This causes scrolling to be virtually unusable.  I note this is a known limitation of the RadGridView from information from https://docs.telerik.com/devtools/wpf/controls/radgridview/troubleshooting/performance 

We have had to remove the alternating row styles from our current product while porting to the RadGridView.  I am requesting if this issue is going to be fixed in the future anytime soon.

The expanded state of the hierarchical item is not preserved when searching thought search panel for something that is not found and clearing search text.

When you define a style targeted at GridViewCell with a color without transparency, horizontal grid lines are hidden.

Currently search tries to match the search value to the complex object value, which always provides negative results. Adding such property will enable search over a primitive type, or string property of the given object.

If you set BorderThickness through a custom CellStyle, the left border is overwritten by our code. 

Full error message: No generic method 'Sum' on type 'System.Linq.Enumerable' is compatible with the supplied type arguments and arguments. No type arguments should be provided if the method is non-generic."

Showing in design time, working at run time.