Slow Power BI reports
A slow report is rarely one big mistake. It is usually five small ones stacked on top of each other.
Where the time usually goes
- A model with high-cardinality columns that nobody uses
- Measures that iterate over millions of rows when a simpler pattern exists
- Too many visuals on one page, each firing its own query
- Bidirectional relationships and many-to-many links in the wrong places
- Import, DirectQuery and Direct Lake chosen by habit rather than need
How we approach it
- Measure first Capture timings with Performance Analyzer and DAX Studio so we fix the real bottleneck.
- Slim the model Remove unused columns, fix data types, reduce cardinality, move logic upstream.
- Rewrite the heavy measures Replace expensive patterns and document what changed and why.
- Hand over Before and after timings plus a short guide so it stays fast.
Free tip: open Performance Analyzer, press Start recording, click around, and sort by duration. The slowest visual is rarely the one you suspect.