# `Excessibility.TelemetryCapture.Analyzers.RenderEfficiency`
[🔗](https://github.com/lessthanseventy/excessibility/blob/v0.18.1/lib/telemetry_capture/analyzers/render_efficiency.ex#L1)

Analyzes render efficiency by detecting wasted renders.

A "wasted render" is a render that repaints identical state — nothing
changed since the view last rendered. Crucially this is measured against
the **previous render in the same view**, not the immediately preceding
timeline event: LiveView captures a `handle_event` and its resulting
`render` as two events, so the render's own diff-vs-previous is empty even
though the interaction genuinely changed state. Counting that render as
wasted would flag every `render_click`/`render_submit` in a healthy test
(issue #142). The first render in a view (the initial paint) is never
wasted.

## Thresholds

- Warning: 3+ wasted renders
- Critical: >30% of renders are wasted

## Output

    %{
      findings: [
        %{
          severity: :critical,
          message: "3 of 5 renders (60%) had no state changes",
          events: [2, 4, 5],
          metadata: %{wasted_count: 3, total_count: 5}
        }
      ],
      stats: %{
        render_count: 5,
        wasted_render_count: 3,
        efficiency_ratio: 0.4
      }
    }

# `analyze`

# `default_enabled?`

# `name`

---

*Consult [api-reference.md](api-reference.md) for complete listing*