How to fix low performance score on Shopify

Steps for Shopify

1. Audit apps: Admin → Apps → remove every app you no longer use actively; each installed app injects JS on every storefront page.
2. Switch to a performance-optimised theme: Online Store → Themes → Explore free themes → choose Dawn (Shopify's reference theme, built for Core Web Vitals). Dawn scores 90+ on mobile out of the box.
3. In your theme's Liquid, ensure all <img> tags use loading='lazy' for below-the-fold images and include explicit width and height attributes to prevent CLS. Dawn does this by default.
4. Use Shopify's built-in image CDN: when you reference images via {{ image | image_url: width: X }}, Shopify automatically serves WebP via its global CDN — never hotlink external image sources.
5. Install a trusted performance app such as Crush.pics or TinyIMG to bulk-compress existing product images, and enable lazy loading store-wide.
6. Defer third-party scripts: in theme.liquid, move non-essential <script> tags to just before </body> and add the defer attribute.
7. Enable Shopify's built-in speed optimisations: they are on by default (CDN, HTTP/2, GZIP) — verify nothing has been overridden in Settings → Files or a custom app.
8. Re-check: use PageSpeed Insights on your live store URL to confirm improvement.

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.