In our v16.1 release we have introduced a very nice feature to improve the U.I experience on the LookUpEdit, ComboBoxEdit and ListBoxEdit.
We call it asynchronous server mode and it means that we use our server mode functionality for the data being shown in the dropdown pane.
Server mode is a very clever way of selecting small chunks of data to populate the visible area of the control. All data-aware operations like sorting, filtering and grouping are being performed in a background thread. This results in an instant feedback U.I. experience for the end-user as the editor and application will always remain responsive for user actions.
When such an operation is in progress, we provide visual feedback in the form of an animation to indicate the status of the operation.
When editors operate in server mode they also support auto complete when the dropdown is closed.