When performance is a concern with larger datasets and calculations that must be a part of the data model, impacting relationships and measures, Power Pivot (DAX Calculated Columns) is perfect.
For data transformation prior to loading into the model, Power Query (M-based Calculations) works best, particularly for basic transformations, data cleaning, and filtering.
For intricate model calculations, use Power Pivot; for data preparation prior to model entry, use Power Query. Data governance and performance are maximized when both tools are used together.