A Power BI development company optimizes dashboard performance by minimizing complex DAX calculations, limiting visuals per page, and optimizing data models. They use techniques like query folding to push data transformations back to the source, reducing load times. Aggregating data at the source, implementing incremental refreshes, and removing unnecessary fields also improve performance. Developers might utilize DirectQuery for large datasets to avoid data duplication. The goal is to ensure that the dashboards load quickly and efficiently, offering a smooth user experience.