Marco Russo helps us tune Power BI reports containing a large number of card visuals:
Every visual element in a Power BI report must complete a number of tasks to provide the expected result. Visuals showing data must generate one or more DAX queries to retrieve the required measures applying the correct filters. The execution of these queries increases the waiting time for the end user, and increase the workload on the server, especially when multiple users access a published report at the same time. In order to improve the performance and the scalability of a report, the best practice is reducing the number of visuals consuming data published in a page of a report.
The focus is on a single page of the report. Power BI only gets data and build the visualizations required for the active page of a report. When the user switches the focus to a different page, the waiting time only depends on the visuals of the new page. The content of other pages of the same report is not relevant for the performance. The goal is reducing the number of visuals in a single page of a report. This could be challenging in order to obtain the same report layout, but we can look for the right visualization once we realize that the number of visuals in the same page is negatively affecting the user experience.
Less is more here.