Performance Optimisation and Core Web Vitals for Modern Web Platforms

The usual sign is not one bad Lighthouse report. It is a commercially important route that feels slower after changes, slips in field data, or keeps exposing the same performance debt across templates, scripts, images, fonts, and data loading.

Route‑level performance work for modern front ends where field data, Core Web Vitals, scripts, fonts, images, data loading, or templates are weakening important user journeys.

Short Answer

Broad performance work starts with affected routes and real user journeys, not a generic tidy‑up. LCP, INP, and CLS problems usually come from rendering, images, scripts, fonts, data loading, layout behaviour, or third‑party code, but one global optimisation rarely fixes every page. I connect the metric to a route, template, or release change, then prioritise fixes the team can verify in production.

Why It Matters

For product and commercial teams, the value is less friction: I trace slow routes, heavy scripts, and unstable templates back to the choices affecting conversion, trust, and release confidence.

Where This Fits

Core Web Vitals diagnosis across important templates, release changes, redesigns, and migration work.
JavaScript, image, font, caching, data‑loading, and third‑party script changes tied to real user impact.
Performance reviews for live Next.js and modern front‑end stacks where field data and commercial journeys both matter.

What I Look at First

I start with affected routes, field data, the LCP element, INP interaction paths, CLS sources, and whether the problem is visible on a commercial journey.
Then I work through rendering, images, fonts, third‑party scripts, caching, data loading, deployment history, and production reproduction rather than treating Lighthouse as the whole answer.
Where performance overlaps with crawlability, rendering, or structured data, I use the Technical SEO Audit Checklist for React and Next.js Websites to keep the checks connected.

Common Engagements

Route‑level investigations after a launch, redesign, or release changes field data.
Performance audits that turn LCP, INP, CLS, and script cost into fixes ordered by journey value and implementation risk.
Hands‑on remediation where the most likely field‑data improvements require code, content, script, image, or release changes.

What Usually Changes

Routes, templates, assets, scripts, and rendering paths that create regressions are isolated.
Lab scores, field data, and local reproduction evidence are separated so the team can focus on real bottlenecks.
Fixes are prioritised by user impact, commercial exposure, and engineering complexity.
The team has a defensible plan for images, scripts, caching, rendering, and release verification.
Release confidence improves without chasing arbitrary performance scores.

How This Usually Works

Technical Diagnostic
A focused review of affected routes, templates, deployment behaviour, crawl signals, CMS behaviour, performance bottlenecks, or code paths, followed by a prioritised fix plan the team can take into delivery.
Recovery Sprint
A short, concentrated engagement for a defined technical SEO, performance, CMS, Vercel, migration, or production issue where the business needs the cause isolated and the first fixes moved quickly.
Embedded Delivery Support
Senior hands‑on support inside an existing team where architecture, implementation, review, and delivery judgement all matter, especially when the work cannot be handed over as isolated tickets.

This May Not Be the Right Fit If

You only need a one‑off Lighthouse report and do not yet have room to change code, content, scripts, images, or release behaviour. If a real regression needs diagnosis, Next.js Core Web Vitals Regression Fix is the better starting point.
The team needs cosmetic speed advice rather than diagnosis tied to field data, templates, and user journeys. If the pressure is mainly third‑party scripts, Third‑Party Script Performance Optimisation is the more focused route.

Talk to me about your performance problem

A short description of the affected route, metric, or recent release is enough. I'll read it and suggest the next step.

Get in touch

Related Case Studies and Project Work

The Optimisation and Rebrand of johnlewis.com
On John Lewis, Core Web Vitals and front‑end optimisation work on high‑traffic retail pages left little room for regressions in speed, stability, or search visibility.
View case study
A New User Experience and Features for Selfridges
At Selfridges, e‑commerce front‑end work had to keep perceived speed, release quality, and commercial flows stable under pressure.
View case study
A Complete Migration and Replatform for Nando’s
On Nando’s restaurant pages, speed, structured data, and local discovery were handled as one customer path rather than separate score‑chasing exercises.
View case study