A one-second delay in your Shopify store’s load time reduces conversions by 7%. A store that loads in 2 seconds converts at 15% — the same store loading in 5 seconds converts at 5%. Page speed is not a nice-to-have; it is one of the highest-ROI optimisations you can make. Here is how to find your speed issues and fix them.
Measure Your Current Speed First
Before fixing anything, benchmark where you are. Test your store at Google PageSpeed Insights — it gives you separate scores for mobile and desktop and identifies the specific issues slowing you down. Also test at GTmetrix which provides waterfall charts showing exactly which resources load slowly. Check your mobile score specifically — Google ranks the mobile version of your store, and mobile scores are typically 30 to 40 points lower than desktop.
Fix 1: Compress and Resize Your Images
Unoptimised images are the single most common cause of slow Shopify stores. Shopify automatically serves images in WebP format (a highly compressed modern format) for browsers that support it, but your original files still need to be reasonably sized before upload. Before uploading product images, resize them to a maximum of 2048 x 2048 pixels and compress using TinyPNG.
For existing stores with large image libraries, install Crush.pics or ImageOptim from the Shopify App Store. These apps compress your existing media library in bulk and auto-compress future uploads.
Fix 2: Audit and Remove Unused Apps
Every installed Shopify app — even apps you no longer actively use — may be loading JavaScript and CSS on your storefront. A store with 30 installed apps can have 20+ extra script files loading on every page visit. Go to your Apps section and uninstall anything you are not actively using. Uninstalling (not just disabling) removes the code from your theme.
For apps you do need, check whether their scripts load on all pages or only relevant ones. Review app scripts do not need to load on the checkout page. Loyalty app scripts do not need to load on the blog. Use Plug In Speed to get a detailed breakdown of which apps are slowing your store and by how much.
Fix 3: Switch to a Faster Theme
Some Shopify themes are significantly faster than others. Shopify’s own free themes (Dawn, Craft, Sense) are highly optimised and score well on PageSpeed by default. Many premium themes from third-party developers add animation, parallax effects, and custom JavaScript that dramatically slows load times. If your theme scores below 50 on Google PageSpeed mobile, switching themes may be the fastest single fix available.
Fix 4: Enable Lazy Loading for Images
Lazy loading delays the loading of images that are below the fold (not visible without scrolling) until the user scrolls down to them. This means the critical above-the-fold content loads first and fast. Most modern Shopify themes have lazy loading enabled by default. Check your theme settings — if it is not enabled, add loading=”lazy” to your image tags in the theme code, or use an app like Lazy Loading Images.
Fix 5: Reduce Render-Blocking Resources
Render-blocking JavaScript and CSS files prevent your page from displaying until they fully load. PageSpeed Insights will flag these specifically. The fix is to defer or asynchronously load non-critical scripts. In Shopify, this often means editing how app scripts load in your theme.liquid file — typically adding async or defer attributes to script tags. This is a developer-level fix but has significant impact on mobile load times.
OneOnic builds Shopify stores optimised for speed from the foundation — lightweight theme selection, image optimisation workflows, and careful app management. See our portfolio or contact us to discuss a speed audit of your existing store.
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