Evidence review
What to inspect before changing anything
Start with the delivered website and the real user journey. Record the current state so the team can distinguish an observed problem from an assumption and compare the same surface after deployment.
- 01Collect LCP, INP and CLS by page type
- 02Compare field and lab data
- 03Identify the element, task or shift behind the metric
Implementation
A practical improvement plan
Make the smallest coherent change that solves the observed problem. Keep normal code review, accessibility, security and product checks in the loop instead of optimizing for the scan alone.
- 01Prioritize the largest real-user segment
- 02Fix delivery, main-thread and layout causes separately
- 03Set budgets and monitor regressions
Verification
How to verify the result
Verification should test the intended outcome and the most likely regression. Use the production delivery path whenever headers, caching, rendering or third-party services affect the result.
- 01Re-measure in lab and field
- 02Segment by device and route
- 03Confirm the product behavior stayed correct
Common pitfall
A shortcut to avoid
Optimizing a lab score alone can miss slow real devices, logged-in states and interactions that users actually perform.
Further reading
Primary guidance and references
These sources provide standards, security guidance or the interpretation framework used to keep this guide bounded. Product-specific implementation still requires review in the actual codebase.