A page can have a perfect headline, perfect proof, perfect CTA — and still convert poorly if it loads in 6 seconds. The visitor's patience is finite; performance failures consume it before any content appears.
Most performance issues stem from third-party scripts (analytics, A/B testing, chat widgets, marketing automation) that load before the hero. Each adds 200-800ms. Five scripts and your LCP is over 3 seconds before you have written a single line of HTML.
Cheap wins: serve hero images in AVIF or WebP (50-70% smaller than JPG), subset web fonts to the characters actually used, defer non-critical scripts to after first paint, and inline above-the-fold CSS. Most marketing pages can hit LCP under 2 seconds with these four moves.
How Lytms scores it
Lytms scores performance under the Post-click dimension via the perf-blocker module. The module pulls real-user Core Web Vitals from Google PageSpeed Insights / CrUX, identifies the specific elements driving slow LCP, and surfaces the third-party scripts most likely responsible. Findings ship with the specific element to optimize and the predicted LCP improvement.
See also
From the blog
See page performance on your own page.
One URL. About 2 minutes.