Largest Contentful Paint (LCP)
TL;DR
LCP measures how fast the biggest visible element (hero image, headline) loads. Under 2.5 seconds is good; over 4 seconds means you're losing users.
Explain Simply
LCP is like timing how long it takes for the main dish to arrive at a restaurant. If the big hero image on your page takes forever to show up, visitors lose patience and leave.
LCP measures the render time of the largest content element visible in the viewport. The LCP element is typically a hero image, video poster, or large text block. Good threshold: ≤2.5 seconds, needs improvement: 2.5-4s, poor: >4s.
Common LCP issues: unoptimized images (no compression, no modern formats), slow server response (TTFB >800ms), render-blocking CSS/JS, client-side rendering delays, and lack of image preloading for above-the-fold hero images.
Optimization strategies: preload the LCP image (), use modern image formats (WebP/AVIF), optimize server response time, implement a CDN, inline critical CSS, and avoid lazy-loading above-the-fold images.
⚡Why It Matters
LCP is the most important Core Web Vital for perceived load speed. Pages with LCP ≤2.5s provide a good loading experience for 75% of users. Improving LCP from 4s to 2.5s can increase conversions by 8-15%.
🔍How AiSEO Checks
AiSEO measures LCP via PageSpeed Insights API and CrUX, identifies the LCP element, and suggests optimizations (preload images, optimize server response, lazy load below-fold).
AiSEO Score Impact
Up to 3 points in the Performance category (15% of total score)
Fix Difficulty
Editor: N/A | Developer: Medium | AI Agent: Medium