Performance optimization in Power BI Development Services requires limiting complex queries and unnecessary visuals. Power BI development services should use aggregations and avoid direct query mode when not necessary to reduce report load times. Preprocessing data using Power Query for transformations minimizes real-time processing. Managing DAX calculations efficiently, such as using variables and avoiding full-table scans, also enhances performance. Incremental data refresh strategies ensure reports remain current without overwhelming resources. Regular performance testing and optimizing visual rendering speed by reducing visual clutter are crucial for delivering fast, responsive dashboards.