Diagnose & Resolve Persistent Google Lighthouse LCP Issue on WordPress Site

Diagnose & Resolve Persistent Google Lighthouse LCP Issue on a WordPress Site Project Overview I’m looking for an experienced WordPress performance engineer to diagnose and resolve a persistent Google Lighthouse Largest Contentful Paint (LCP) issue. This is NOT a general website optimisation project. Please do not apply if your standard approach is to recommend image compression, caching plugins, lazy loading, CDNs, or generic PageSpeed improvements. Those areas have already been investigated. I’m looking for someone with strong technical debugging skills who can identify the root cause of this issue, implement the correct fix, and demonstrate a measurable improvement using Lighthouse. ⸻ The Issue Google Lighthouse (mobile) consistently reports: * Performance score: approximately 70–73 * Largest Contentful Paint (LCP): approximately 5.7–6.0 seconds This occurs across multiple pages, including extremely simple pages. ⸻ What Has Already Been Investigated Server Performance * Excellent TTFB (typically 10–50ms) * Backend performance investigated * No significant PHP or database bottlenecks identified Images * Images optimised * Dynamic Srcset enabled * Test page header image is only 29KB * LCP image downloads quickly Lighthouse Typical breakdown: * TTFB: 10–50ms * Resource Load Delay: ~340ms * Resource Load Duration: ~70–110ms * Element Render Delay: typically between 670ms and 1700ms Lighthouse consistently identifies the page header background image as the LCP element. ⸻ Testing Already Completed The issue has been reproduced across: * Homepage * Privacy Policy page * Terms page * Multiple additional pages Pages tested include: * Very simple layouts * More complex layouts * Small header images * Large header images Changing page complexity has had little impact on the reported LCP. ⸻ Changes Already Tested * Image optimisation * Dynamic Srcset * Header configuration changes * Removing the page header * Background image testing * HTML image versus CSS background image testing * Multiple cache clears * Numerous Lighthouse runs after every change None of these changes has materially improved the reported Lighthouse LCP. ⸻ What I Need I want someone who can: 1. Investigate the issue thoroughly. 2. Identify the root cause with technical evidence. 3. Test their proposed solution. 4. Implement the fix. 5. Demonstrate a measurable improvement in Lighthouse LCP using before-and-after reports. 6. Explain exactly what was changed and why it worked. This is a results-based project. I am not looking for a generic optimisation checklist—I am looking for someone who can identify and fix the specific cause of this persistent Lighthouse LCP issue. ⸻ Success Criteria The project will be considered complete when all of the following have been delivered: * The root cause has been identified. * The appropriate fix has been implemented. * Before-and-after Lighthouse reports demonstrate a clear improvement in the reported LCP. * A summary explaining the root cause, the changes made, and why they resolved the issue. ⸻ Please Only Apply If You Have Experience With * WordPress performance debugging * Google Lighthouse * Chrome DevTools Performance panel * Core Web Vitals * Critical rendering path optimisation * CSS rendering * JavaScript performance * Theme and plugin interaction debugging