Creating an effective Power BI dashboards for a large dataset involves challenges like performance optimization, data loading times, and maintaining responsiveness. Developers must design efficient data models, reduce the complexity of DAX calculations, and implement strategies such as aggregating data or using summarized datasets. Ensuring that the dashboard remains user-friendly while handling vast amounts of data requires careful planning of visuals and interactivity. Additionally, real-time data refreshes must be managed to avoid overwhelming the system, ensuring that the dashboard delivers timely insights without compromising on speed or usability.