Handling large datasets requires expertise in data modeling, indexing, and query optimization. A Power BI developer optimizes performance by reducing dataset size, using aggregations, and implementing incremental refresh. Efficient DAX queries, optimized relationships, and minimizing unnecessary calculations improve dashboard speed. Using DirectQuery instead of Import Mode helps when dealing with real-time data needs. Implementing Power BI developers Premium features like aggregations, dataflows, and hybrid tables enhances performance. Without these optimizations, dashboards may experience slow load times, poor user experience, and increased cloud computing costs, leading to inefficient decision-making.