A slow report erodes trust faster than almost anything else. If your users are staring at spinners, they stop exploring — and an insight nobody waits for is an insight nobody acts on. Here are five performance tips we reach for again and again on real client work.
1. Trim your model before you tune your DAX
The single biggest performance lever is usually the data model, not the measures. Remove columns you don’t use, avoid high-cardinality text columns (especially unique IDs you never display), and prefer a clean star schema over a tangle of relationships. A leaner model compresses better and queries faster.
2. Mind your cardinality
High-cardinality columns bloat the model and slow down everything downstream. Split datetime columns into separate date and time columns, round numeric values where precision isn’t needed, and let your date dimension do the heavy lifting instead of calculating dates on the fly.
3. Let measures do the work, not calculated columns
Calculated columns are computed at refresh and stored in the model, inflating its size. Measures are computed at query time and cost nothing at rest. As a rule of thumb: if you’re aggregating, use a measure; only reach for a calculated column when you genuinely need a row-level value to slice or filter by.
4. Use variables to stop repeating yourself
Storing an intermediate result in a DAX variable with VAR means the engine evaluates it once instead of recalculating it every time it appears. Variables also make your measures dramatically easier to read and debug — a rare win-win.
5. Measure what you’re optimising
Don’t guess. Use Performance Analyzer in Power BI Desktop to see exactly which visuals and queries are slow, and DAX Studio to inspect the queries they generate. Optimise the worst offender, re-measure, and repeat. You’ll often find one or two visuals account for most of the wait.
The bottom line
Performance work compounds: a lean model makes your DAX faster, and fast DAX makes your reports feel effortless. Start with the model, measure as you go, and your users will thank you for it.
Want report templates that come performance-tuned out of the box? Take a look at our Power BI templates.