To properly visualize resultset DBeaver needs metadata information about underlying tables/types.
In most cases "late binding" is not required because tables consists from simple columns (numbers, varchars). But if you use objects/structures, arrays, references and other complex data types then DBeaver needs to read information about these types from Oracle system tables. It could take some time. Usually it is performed in 100-500ms. But if you are working with remote database with poor connection - it can take much more time. But what choices do we have?
Did you notice what exactly query works so long? To see what actual query is executing:
1. Go to Preferences->Common->Query Manager. Enable all checkboxes in "Query Types" and "Object Types".
2. Open Query Manager view (in main menu "Window").
3. Restart DBeaver. Execute your select statement.
4. See what metadata queries are executed during late binding.
If you'll find problem query - please post it here.