# Performance baseline is documented

- **Pattern:** `ab-002192` (`pre-launch.final-verification.performance-baseline`)
- **Severity:** low
- **Lifecycle:** active
- **Last modified:** 2026-04-18
- **Canonical URL:** https://auditbuffet.com/patterns/ab-002192
- **License:** CC-BY-4.0 — attribute to AuditBuffet Pattern Catalog (https://auditbuffet.com/patterns/ab-002192)

## Why it matters

Without a performance baseline before launch, any future deployment that regresses Core Web Vitals (LCP, CLS, INP) goes undetected until users notice the slowness. ISO 25010:2011 performance-efficiency.time-behaviour defines response time as a measurable quality attribute — not measuring it means you cannot detect regressions. Beyond technical debt, Lighthouse performance scores directly influence Google Search ranking via Core Web Vitals signals: an unmeasured, slow launch can suppress organic traffic from day one without any visible indicator to the developer.

## Severity rationale

Low because the absence of a performance baseline produces delayed detection of regressions rather than immediate harm, but it prevents the team from distinguishing intentional performance trade-offs from accidental degradation.

## Remediation

Record a Lighthouse baseline against your production URL immediately after launch and store the report in the repository.

```bash
# Record baseline — save output to repo
npx lighthouse https://yoursite.com --output=json --output-path=./lighthouse-baseline.json
```

For automated enforcement, install `@lhci/cli` and create `.lighthouserc.json` with performance score thresholds — Lighthouse CI runs on every PR and fails the build if scores drop below your baseline. At minimum, add your performance targets to the README: `Target: LCP < 2.5s, CLS < 0.1, Performance score ≥ 80`. Add the `web-vitals` package to track real-user Core Web Vitals from production traffic.

## Detection

- **ID:** `performance-baseline`
- **Severity:** `low`
- **What to look for:** Count all performance measurement configurations. Enumerate whether Lighthouse scores or Core Web Vitals baselines have been recorded for the production site. Check for any performance documentation: a Lighthouse report in the repo, performance metrics in README, a `performance.md` or similar document, or comments in code noting expected load times. Look for Lighthouse CI configuration (`.lighthouserc.json`, `.lighthouserc.js`) or web-vitals tracking integration (`web-vitals` in dependencies, `onCLS`, `onFID`, `onLCP` function calls).
- **Pass criteria:** Some evidence of performance measurement or baseline exists: a Lighthouse CI config, web-vitals tracking in the codebase, a performance report file, or README documentation of performance targets. At least 1 performance baseline measurement must be recorded with Lighthouse score at least 60.
- **Fail criteria:** No evidence of any performance measurement or baseline documentation.
- **Skip (N/A) when:** Skip for API-only projects with no user-facing pages. Signal: project type is `api` or `cli` with no HTML pages.

- **Cross-reference:** For error monitoring that includes performance, see `error-monitoring`. For analytics, see `analytics`.
- **Detail on fail:** `"No performance baseline documented — you will not know if a future change regresses load time without a reference point"`
- **Remediation:** Having a performance baseline before launch means you can detect regressions immediately. This doesn't require extensive tooling:

  ```bash
  # Record baseline with Lighthouse
  npx lighthouse https://yoursite.com --output=json --output-path=./lighthouse-baseline.json
  ```

  1. Run Lighthouse on your production URL after launch and save the report (export to JSON or HTML).
  2. Add Lighthouse CI to your repo for automated checks on every PR: install `@lhci/cli` and create `.lighthouserc.json` with your performance thresholds.
  3. Add `web-vitals` tracking to log Core Web Vitals (LCP, FID/INP, CLS) from real users.
  4. At minimum, document your target metrics in README: "Target: LCP < 2.5s, CLS < 0.1".

  For a comprehensive analysis of performance and load readiness, the Performance & Load Readiness Audit covers this in depth.

## External references

- iso-25010 performance-efficiency.time-behaviour

Taxons: performance, observability

HTML version: https://auditbuffet.com/patterns/ab-002192