Phil Seamark doesn’t have time to wait for Power BI to count:
This article aims to show how you can speed up distinct count calculations in Power BI using the built-in user-defined aggregations feature. The user-defined aggregation feature in Power BI is designed to work with direct query models and usually gets used for calculations such as SUM, MIN, MAX etc. However, it can also work well for distinct count calculations using the pattern shown in this article.
It’s an interesting partial aggregation approach which works really well when the distinct count is a small percentage of the total.