When RadGridView is bound to a collection of 60 000 records the difference in the sorting time between using a ProBindingSource and a DataTable is massive. Changes in any core logic in both internal implementations, RadGridView and ProBindingSource, isn't so easy as it looks. Both products have been for a very long time on the market designed to cover the main scenarios of the target customers groups for which they are developed.
By default, if the rows count is less than 10 000 we use quick sort to order the items in the grid. If there are more items we use Red-Black tree. This is controlled by the UseHybridIndex property.
(radGridView.MasterTemplate.ListSource.CollectionView as GridDataView).UseHybridIndex = false;
However, both of algorithms use non-linear data access. If the ProBindingSource is not optimized to get data not linearly, the performance wouldn't be satisfactory.
That is why we have introduced the BypassSort functionality to cover this case after cooperation with the OE developers. Thus, our RadGridView won't perform any logic for sorting and the whole time necessary for sorting will depend on the DataSource itself (ProBindingSource in your case) and how this collection sorts its items: https://docs.telerik.com/devtools/winforms/controls/gridview/sorting/basic-sorting
In the current version of Telerik UI for WinForms suite, the BypassSort property is ignored if the BypassFilter is not set to true as well. Hence, the sorting will be still slow.
Both properties shouldn't affect each other and if a developer wants to improve only the sorting performance, it is expected to enable only the ByPassSort property.