Chris Webb explains what a new metric means:
What does WaitTime represent? Here’s the technical explanation: it’s the wait time on the query thread pool in the Analysis Services engine before the query starts to run. But what does this mean for you as someone trying to tune DAX queries in Power BI?
Chris provides an examplation of exactly that. This tracking of noisy neighbors is interesting, as it would provide insight if you’re noticing variance in dataset refresh times.