To optimize performance, Power BI consultants implement techniques such as reducing data granularity and using aggregations for faster queries. They configure incremental refresh for large datasets and optimize DAX expressions to minimize computational overhead. Query folding is enabled where possible to push data transformations back to the source. Power BI consultant also use performance analyzer tools to identify and resolve bottlenecks in visuals and queries. By using these methods, they ensure that Power BI reports are both highly responsive and capable of handling complex data models efficiently.