A clear scope
What PERFORMANCE means here
Performance work focuses on how real customers experience the storefront.
Core Web Vitals and Ecommerce Performance owns the specific workflow and deliverables described below; related pages supply complementary work and should not duplicate its scope.
The buyer problem
Where the work makes a difference
A single fast lab run can hide slower real devices, heavy third-party scripts or layout shifts during shopping. Performance work needs field evidence and checks that customer tasks still work after each change.
Use field data to identify affected templates and laboratory tools to diagnose causes. Prioritize changes with engineering teams and verify that improvements survive real devices, networks and interactions.
The specific work
What we investigate and improve
- Baseline field LCP, INP and CLS by device and template.
- Diagnose images, scripts, rendering, third-party tools and layout shifts.
- Prioritize implementation with performance budgets.
- Monitor releases and validate real-user outcomes.
BrownBag’s approach
From evidence to useful improvements
Establish field and lab baselines
Review available real-user measurements by device and template, then reproduce important issues with diagnostic tools. Record data gaps where the store lacks sufficient field observations rather than inventing a passing score.
Fix the largest experience costs
Prioritise image loading, script execution, rendering and layout stability with developers. Check the commercial role of third-party widgets before removal and define performance budgets for agreed templates.
Validate beyond a single run
Repeat representative lab checks and verify shopping tasks after release. Review field data over its collection window, separating immediate diagnostic improvements from evidence about real users.
Your handover
What you receive
- Field/lab baseline and root-cause findings.
- Prioritized performance engineering backlog.
- Template-level performance budgets.
- Post-release verification and regression monitoring plan.
Evidence, with context
How we measure progress
- 75th-percentile LCP, INP and CLS
- Affected template coverage
- Real-user latency
- Shopping funnel guardrails
Scope your next step
Bring us the problem you want to solve.
These details help us agree the deliverables, responsibilities and review points:
- Store URL, field performance access where available and device mix
- Theme, app, script and hosting ownership
- A review environment and business-critical journeys to protect
Start with a focused scope. We confirm access, implementation ownership and any platform eligibility before the work begins.
Your questions, answered
What are the current good thresholds?
Google's documented thresholds are LCP at most 2.5 seconds, INP at most 200 milliseconds and CLS at most 0.1, assessed at the 75th percentile.
Is a Lighthouse score enough?
No. Lab tests help diagnose issues, while field data reflects real user conditions. A high score alone does not prove a good experience for everyone.
Will faster pages guarantee higher rankings?
No. Performance is useful for users, but rankings and revenue depend on many factors.