This book is the state of the art of optimizing DAX expressions in Power BI and Analysis Services semantic models. Learn how to locate performance bottlenecks, read the query plan and performance metrics, rewrite the slower part of an expression, and measure the performance improvements. Use tools like Power BI Desktop Performance Analyzer and DAX StudioUnderstand the DAX formula engine Learn characteristics of different storage engines (VertiPaq, DirectQuery over SQL)Read DAX query plansOptimize common DAX constructsSolve security performance issuesImprove DirectQuery response timeControl the data placement in composite models to avoid bottlenecksPrerequisites: proficiency in DAX and SQL (for DirectQuery), understanding of the Tabular engine used by semantic models, and familiarity with DAX Studio.