LCP measures how long it takes the largest visible element, usually a hero image or heading, to finish loading. Google's threshold for a good mobile LCP is 2.5 seconds. The most common fix is compressing or resizing the largest image on the page.
Why it matters
LCP is one of Google's Core Web Vitals and a confirmed part of the page experience signal. A slow LCP can affect ranking, and it is also the part of "site speed" a visitor actually notices: how long they stare at a mostly blank page.
LCP is measured on mobile, on a throttled connection, which is usually the worst-case and most common scenario for real visitors.
How AuditCrow checks this
AuditCrow runs a real PageSpeed/Lighthouse measurement against the page on a simulated mobile connection and reads the LCP timing back, alongside the element Lighthouse identifies as the LCP candidate.
How to fix it
- 1Identify the LCP element. It is usually a large hero image, a background image set in CSS, or a large heading rendered after a web font loads.
- 2If it is an image: compress it (tools like Squoosh or TinyPNG), serve it in a modern format such as WebP or AVIF, and size it to the space it actually occupies rather than shipping a much larger original.
- 3Avoid lazy-loading the LCP image itself. Lazy-loading is for images further down the page; applying it to the very first visible image delays the one metric you are trying to improve.
- 4If the LCP element is text, check whether a web font is blocking render. `font-display: swap` (or preloading the font) lets text show in a fallback font immediately rather than waiting.
- 5In WordPress, an image-optimisation plugin (ShortPixel, Smush) or a caching plugin with image handling covers most of this. Check the theme is not loading a full-resolution header image at a smaller display size.
- 6Re-run a real PageSpeed test after each change; lab scores can vary run to run, so look for a consistent improvement rather than a single reading.
Related terms
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