LCP causes

web.dev breaks LCP into four sub-parts: time to first byte, resource load delay (how late the browser discovers the LCP resource), resource load duration and element render delay. The fixes follow them: cut server response time (TTFB ≤ 800 ms is good, > 1800 ms poor), make the LCP image discoverable in the initial HTML and never lazy-load it (fetchpriority=high helps), reduce or defer render-blocking CSS and JavaScript, and render the main content on the server rather than after client-side JavaScript. Google's research notes load duration is usually not the main bottleneck.