Improve measured performance without damaging the website

Lead: R06. Consulted roles: R01, R03, R04, R05, R06, R07, R08, R16, R20, R21, R25, R26. Mode: read-only diagnosis until actual authorization.

Entry condition

A measured field or lab bottleneck affects representative customer journeys. The goal is not an isolated score improvement at any cost.

Sequence and ownership

1. Define the baseline

R06 separates field and lab data, records routes/templates, windows, devices and tool versions. Missing field data is unknown, not a passing metric.

2. Find the dominant cause

Inspect primary-content delivery, interaction blocking, layout movement, fonts, images, scripts and cache behavior using actual traces.

3. Review interfaces

R01 reviews runtime/cache changes; R20 checks private response exposure; R08 checks meaningful content and directives; R04/R07/R05 protect actual interactions.

4. Change one controlled unit

Use a minimal reversible proposal. Record baseline and candidate under comparable conditions. R21 executes critical journey regressions; R16 checks event integrity.

5. Release and observe

R25 sequences the authorized change; R26 checks the declared build. Report immediate lab results separately from later sufficiently sampled field results.

Evidence package

Preserve task/run IDs, exact environment/build, timestamped observations, safe synthetic inputs, expected versus observed state, tool/browser versions, raw private artifacts and separately hashed public-safe redactions. Record unavailable tools and tests not executed. Attach the handoffs rather than compressing distinct observations into one success flag.

Acceptance

• The claimed improvement matches a reproducible method
• No inquiry, accessibility, privacy, browser or URL-policy regression
• Field claims use available appropriate field evidence

Stop or block

Do not cache personal API responses, remove essential content, defer critical behavior or claim conversion uplift from a lab score. If the historical field window is incomplete, state that explicitly.

Role and source references

• R01 — Site Reliability Engineer
• R06 — Web Performance Engineer
• R20 — Application Security/Privacy Engineer

Primary-source IDs: D09, D10, D05, D11. See the source register for URLs, scope and currentness boundaries. The sequence is custom operating design; it is not a promise that every case has the same cause.