# Speed up a slow Power BI or Tableau dashboard

Diagnoses why a BI report loads slowly and gives a ranked list of fixes across data model, queries, calculations, and visuals.

- Topic: Data & Analysis
- Framework: RTF
- Level: Standard
- Tags: Data & Analytics, Design, Analyze, Fill-in Template
- Source: https://www.thinkwithprompt.com/prompts/speed-up-a-slow-power-bi-or-tableau-dashboard

## Prompt

```text
Help me speed up a slow BI dashboard.

**Tool:** [Power BI / Tableau / Looker / other]
**Connection mode:** [import/extract, DirectQuery/live, mixed]
**Symptoms:** [e.g. "page takes 25 seconds to load", "slicers lag", "refresh times out"]
**Data model:** [tables, row counts, relationships, cardinality of key columns]
**Heavy calculations:** [PASTE slow DAX measures, calculated fields, or LOD expressions]
**Page design:** [number of visuals per page, filters, custom visuals]
**Performance diagnostics:** [PASTE Performance Analyzer, Performance Recorder, or query log output if available]

Diagnose across these layers:
1. **Data model:** unnecessary columns, high-cardinality columns (timestamps, IDs, long text), wide flat tables vs. a star schema, bidirectional or many-to-many relationships, calculated columns that should be done upstream.
2. **Source and queries:** DirectQuery hitting slow views, missing aggregations, unpushed filters, no incremental refresh.
3. **Calculations:** iterator functions over large tables, repeated sub-expressions (use variables), complex row-level logic, nested LODs or table calculations.
4. **Visuals:** too many visuals per page, high-cardinality tables, heavy custom visuals, many slicers cross-filtering each other.
5. **Filters:** context filters vs. regular filters, filters on calculated fields.

Return:
- The likely bottlenecks, ranked by impact, with the evidence from what I shared.
- A fix list: Change | Layer | Expected impact | Effort | Risk.
- Rewritten versions of any slow calculations I pasted.
- How to measure before and after so I can prove the improvement.
```

## What to fill in

- Power BI / Tableau / Looker / other
- import/extract, DirectQuery/live, mixed
- tables, row counts, relationships, cardinality of key columns
- number of visuals per page, filters, custom visuals

Free to copy and use. From ThinkWithPrompt (https://www.thinkwithprompt.com/), a library of 2,663 curated AI prompts.