Phil Seamark has a dashboard which will help understand Power BI dataset refresh times:
Have you ever wondered why a Power BI dataset refresh was taking so long? And more specifically, how much time did the refresh spend on various sub-tasks that aren’t that visible to you via the web-portal?
This article shares a technique you can use to capture events fired during a Power BI refresh and use the results in a Power BI report visualise the results. Have to love the idea of using Power BI to optimise and improve Power BI.
Click through to get the Power BI report and get step-by-step instructions on how to use it.