TopN with Direct Query

I am using Direct Query with up to several million rows. I am having issues creating a visual of Top 5 Industry Codes by count by highest number of Unique IDs.

I need to filter out duplicate Codes before I filter on industries, so the Unique IDs count is calculated by this measure:

Measure for # Unique IDs =
var dc = Calculate (DISTINCTCOUNT('Table'[UniqueID]),Filter('Table'[UniqueID] <> BLANK ()))
return IF(ISBLANK(dc), dc, dc)

Then I am using the filter pane on a bar chart to find the Top 5 by count of Unique IDs. It is causing my page to load very slowly ... I imagine a measure will make this more efficient but when I try to use TopN function I can't get the measure right when using Direct Query.

I prefer to do this within the report with my original table, but as I understand it, I also have these options and need to know which will is best for performance:

-- Write a SQL query when connecting to the db to create a separate view/table in my report
-- Duplicate the main table after import, delete the rows I don't need and go to Home --> Keep Rows --> Top 5

Image of what I need and the current filter:

https://www.dropbox.com/s/4luq2aektl8lbn4/TopN_DirectQuery.jpg?dl=0

Help is much appreciated!

Carly