# Work repeated for nothing

Prompt · Performance and scale · P04

Finds work redone on every request or screen redraw when nothing it depends on changed.

## Prompt

```text
Identify expensive work that is repeated despite unchanged inputs. Investigate caching, memoization, batch operations, and incremental computation before recommending changes.
```

**What it returns:** The operation, how often it runs, how often its inputs change, and its measured cost.

**Skip it when:** Work that is already cheap, where saving results would add a risk of stale data for little gain.

**Tools:** A profiler or request logs to count repeats.

**Watch for:** A cache is a second source of truth. Any cache proposal must say who invalidates it and when.

**Changes:** Changes nothing

**Sessions:** One session

## Related

- [Two systems that disagree](https://atlasscope.dev/prompts/two-systems-that-disagree): Finds data kept in two places (a saved copy and a table, the browser and the server) that can quietly disagree.
- [Slowest journeys, end to end](https://atlasscope.dev/prompts/slowest-journeys-end-to-end): Shows where the seconds go on the paths people actually use.
- [Stop rewriting data that hasn't changed](https://atlasscope.dev/prompts/stop-rewriting-data-that-hasnt-changed): Upserts and updates run at high volume, imports are costly, or vacuum and write-ahead log churn look high.

Source: https://atlasscope.dev/prompts/work-repeated-for-nothing