How to fix low performance score on BigCommerce

Steps for BigCommerce

1. Use Cornerstone theme (BigCommerce's official reference theme): Storefront → Themes → select Cornerstone — it ships with lazy-loaded images and CDN-optimised assets.
2. BigCommerce automatically serves all store assets via Akamai CDN and delivers images via its built-in Image Manager CDN — ensure you are not hot-linking external image URLs in product descriptions.
3. Optimise product images before uploading: target ≤ 200 KB per image at actual display size; BigCommerce's Image Manager will serve them at the right dimensions.
4. Reduce third-party script load: Storefront → Script Manager → review every script; delete or disable any that are unused. Set non-critical scripts to load in the Footer and mark them as 'Deferred'.
5. Enable Cloudflare (free or paid) in front of your BigCommerce store via CNAME setup for additional edge caching and Brotli compression: Settings → Domains → follow the BigCommerce Cloudflare setup guide.
6. Check App Marketplace for performance-focused image apps (e.g., Amasty Image Optimizer equivalent on BC App Store) if you have a large product catalogue.
7. Re-test with PageSpeed Insights; monitor Core Web Vitals in Google Search Console → Experience → Core Web Vitals.

What is low performance score?

The Lighthouse Performance Score (shown in Google's PageSpeed Insights tool) is a single number from 0–100 that summarises how fast your web page loads and responds for real users — especially on mobile. It is calculated from five timing metrics, with the three Core Web Vitals (Largest Contentful Paint, Interaction to Next Paint, and Cumulative Layout Shift) carrying the most weight. A score below 50 is considered "Poor" by Google; a score above 90 is "Good." Think of it as a health-check report card for your page's speed: every point you gain means real customers are waiting less and leaving less.

Google officially uses page experience signals — including Core Web Vitals — as a ranking factor, meaning a very low score can directly suppress your position in search results and reduce organic traffic. Beyond rankings, a slow page destroys conversions: industry data consistently shows that each additional second of load time drops conversion rates by 10–20 %, and mobile shoppers are the most sensitive. A score of 8/100 on mobile means the vast majority of your mobile visitors are likely bouncing before they even see your products, costing you both ad spend and organic sales. Closing this gap is one of the highest-ROI technical improvements an ecommerce store can make.

See the complete Low performance score guide for every platform and the full background.