I see. Not sure if this is possible with your datasource, but have you tried using the pipe delimited options (in a multiline plain text field)? – this way your datasouce could be stored in one list item even if it is hundreds of options – and this way the sort order is exactly as you type them into the textarea.
You would still have to run 10 queries to fill the dropdowns, but when the query only pulls in one list item it should be pretty lightweight.
Alexander