A slow store costs you twice: shoppers leave before the page finishes loading, and Google uses page experience as one of its ranking signals. The fix is rarely "buy a faster theme". It's usually a handful of apps, images and scripts that pile up over time. Here's how to find what is slowing your Shopify store down and fix it, step by step.
First, measure the right way
Use PageSpeed Insights, but read it correctly
Run your homepage, one collection and one product page through PageSpeed Insights. Look at the top section first — "Discover what your real users are experiencing". That's real visitor data from Chrome, and it's what Google actually uses. The lab score below it is a simulation and can jump around between runs.
Know the three numbers that matter
Google's Core Web Vitals are the metrics to watch:
- LCP (Largest Contentful Paint) — how fast the main content appears. Good is 2.5 seconds or less.
- INP (Interaction to Next Paint) — how quickly the page reacts when someone taps or clicks. Good is 200 ms or less.
- CLS (Cumulative Layout Shift) — how much the page jumps around while loading. Good is 0.1 or less.
Shopify also has a speed report under Analytics → Reports → Online store speed, which is useful for spotting trends after you make changes.
Remove what you don't need
Audit your apps
Every app that adds something to your storefront — reviews, pop-ups, chat, upsells, trackers — usually adds its own JavaScript and CSS to every page. List your apps and ask of each one: "Did this make us money in the last 90 days?" Uninstall the ones that didn't.
Clean up leftover app code
Uninstalling an app doesn't always remove the code it added to your theme. Search your theme files for the app's name, or check Online Store → Themes → Customize → App embeds and turn off anything you no longer use. Leftover scripts can keep loading for months.
Limit third-party scripts
Tracking pixels, heatmaps and chat widgets all load from other servers. Keep the ones you actively use, load them through Shopify's Customer Events where possible, and remove duplicates — it's common to find the same analytics tag installed twice.
Fix your images and media
Right-size images
Shopify's CDN resizes and converts images automatically when the theme asks for the right size. Problems start when a theme loads a full-size image into a small space, or when sliders load every slide at once. Upload sensibly sized source images and make sure your theme uses responsive images (srcset).
Lazy-load below the fold, not above it
Images further down the page should load only when the shopper scrolls near them. But the main hero or product image — usually your LCP element — should load immediately. Lazy-loading the hero image is one of the most common causes of a poor LCP score.
Be careful with autoplay video
A background video on the homepage can look great and still weigh more than the rest of the page combined. If you keep it, compress it, use a poster image, and consider showing a still image on mobile.
Tidy up the theme
Use an up-to-date Online Store 2.0 theme
Older themes often load big libraries like jQuery on every page and have no way to load sections only when needed. A modern theme built on Shopify's current architecture is usually a faster base than an old one with years of patches.
Reduce fonts
Each font weight is a separate file. Two families with two or three weights each is plenty. Use font-display: swap so text shows immediately instead of staying invisible while fonts download.
Stop the layout from jumping
CLS problems usually come from images without a set width and height, banners that appear after the page loads, and late-loading fonts. Reserve space for anything that loads late, and avoid pushing content down with pop-ups on page load.
A simple order of work
- Measure three key pages and write the numbers down.
- Remove unused apps and their leftover code.
- Fix the hero image so it loads first and isn't lazy-loaded.
- Resize heavy images and videos.
- Trim fonts and third-party scripts.
- Measure again a few days later — real-user data takes time to update.
Speed and SEO work together, so pair this with our Shopify SEO checklist. If you'd like it done for you, our Shopify speed & performance optimization service covers the full audit and every fix above.