One of the most important actions to speed up the performance of Power BI reports at runtime is using Aggregations. Aggregations can be used in a model regardless of DirectQuery, Composite model, Import Data or even DirectLake in Fabric.
This is the first video of the performance series that explains how the aggregations can be useful for the performance tuning when dealing with large amount of data and many records.
read my blog article from here:
https://radacad.com/power-bi-fast-and-furious-with-aggregations