DAX Deep Dive 03: Why is Your Power BI Report Crawling? Let’s Solve the Mystery.
DAX Optimization Technique: Execution-Aware DAX Design When a Power BI report is slow, most users suspect the following: Is it because the data volume is too large? Is the visualization too complex? Are functions like SUMX or CALCULATE too heavy? However, the real cause most frequently encountered in practice is something else entirely: the developer is unaware that the engine is performing unnecessary calculations "until the very end." This post addresses exactly that point. Today, we will explore "Execution-Aware DAX Design"—the core of DAX performance optimization—and the "Early Exit" technique, which physically removes unnecessary operations. 1. Why Does DAX Calculate Useless Things Until the End? DAX is inherently a language that "seeks to preserve meaning." While general programming decides its path based solely on the "current value," DAX is a perfectionist that considers data relationships and every possible change. Let’s u...