Growth · Web design and build · 04
Performance engineering and Core Web Vitals
Performance engineering and Core Web Vitals makes every page fast on the devices and connections buyers actually use: largest contentful paint, interaction responsiveness and layout stability measured and kept in the green on mobile, with images, fonts, scripts and styles engineered so that speed is a property of the build rather than a periodic rescue. It is needed when pages are slow on phones, when Core Web Vitals reports show failures, when speed affects rankings, trust or conversion, or when a site is being rebuilt and the performance budget should be set from the start. The work produces a performance budget per page type, the engineering that meets it, measurement with field and lab data, and the check that keeps new pages within the budget.
Scope
What the review covers.
- Performance budget per page type: size, requests, render-blocking resources
- Image strategy: formats, sizing, lazy loading, dimensions to prevent layout shift
- Font loading and script handling
- Critical rendering path and edge caching
- Field and lab measurement: Core Web Vitals, Lighthouse, real-user data
- Build-time checks against the budget
Deliverables
What you receive.
| Deliverable | Form |
|---|---|
| Performance budget | Per page type, enforced |
| Engineering implementation | Images, fonts, scripts, caching |
| Measurement report | Field and lab results, trended |
| Build check | Fails pages that exceed the budget |
Prerequisites
What we need from you.
- Access to the site build and hosting
- Search Console and real-user performance data where available
- Agreement on the target devices and connections
Related
Where this sits.
- Web design and build Service
- Growth Hub
- Accessibility to WCAG 2.2 AA Also
- Multilingual editions and hreflang Also
By David Selakovic · Published 2026-10-16 · Revised 2026-10-16 · Reviewed every 180 days
Questions
Asked before engaging.
What scores do you target?
Core Web Vitals in the green on mobile and Lighthouse performance of 95 or better, measured on real pages, not a test page.
Will third-party scripts be removed?
Each is justified or removed. Most performance problems on marketing sites are tags nobody remembers adding.
Does speed matter for AI citation?
Crawlers have time budgets and engines weight sources that respond. Speed is a trust signal for people and machines alike.