How to fix cwv lcp on BigCommerce

Steps for BigCommerce

1. IDENTIFY LCP IMAGE: Run PageSpeed Insights on your storefront. The LCP is usually the hero carousel image configured under Storefront › Home Page Carousel or a theme banner.
2. CONVERT TO WEBP: BigCommerce's Akamai Image Manager automatically serves WebP/AVIF to supported browsers when you upload standard images — no action needed if you are on a current plan. Confirm by inspecting the hero image URL for a format parameter.
3. UPLOAD OPTIMISED SOURCE: Even with auto-conversion, upload the highest-quality but appropriately-sized source JPEG/PNG (max 1920px wide) via Storefront › Image Manager so the CDN has a good original to compress.
4. PRELOAD: Go to Storefront › My Themes › Edit Theme Files (or use Stencil CLI). Open templates/layout/base.html. In <head>, add: <link rel='preload' as='image' href='{hero image CDN URL}' fetchpriority='high'>. For dynamic images use the Handlebars variable that outputs your carousel image.
5. DEFER JS: In base.html, add 'defer' to non-essential third-party <script> tags. Move analytics and chat widgets to the bottom of <body> or wrap in a setTimeout.
6. NO LAZY-LOAD: Find the carousel/hero img tag in templates/components/ and ensure it has loading='eager' fetchpriority='high'.
7. VERIFY: Re-run PageSpeed Insights; monitor Core Web Vitals in Google Search Console.

What is cwv lcp?

Largest Contentful Paint (LCP) measures how long it takes for the biggest visible element on your page — almost always the hero image or banner — to fully appear in a visitor's browser. Google considers a "good" LCP anything under 2.5 seconds. An LCP of 9+ seconds means shoppers are staring at a blank or partially loaded page for nearly ten seconds before they see your main content. LCP is one of Google's three Core Web Vitals, which are direct ranking signals used in Google Search.

A slow LCP directly hurts your Google rankings because Core Web Vitals are an official page-experience ranking factor — pages with poor LCP can lose positions to faster competitors even with identical content. More critically, research consistently shows that every additional second of load time reduces conversion rates by 2–7%; an LCP of 9 seconds can cost you the majority of mobile visitors who leave before the page even finishes loading. Mobile shoppers are disproportionately affected because mobile connections are slower, and Google indexes the mobile version of your site first. Fixing LCP is one of the highest-ROI technical improvements an ecommerce store can make: faster pages rank higher, bounce less, and convert better.

See the complete Cwv lcp guide for every platform and the full background.