Shopify App Performance: Which Apps Slow Your Store Down

Every Shopify app you install adds code to your store. Some are barely noticeable. Others can drop your score by 20 points. Here is how to find out which.

Why apps hurt Shopify speed

Shopify's app ecosystem is one of its greatest strengths and one of its biggest performance liabilities. Each app you install can inject JavaScript, CSS, and tracking pixels into your storefront — and many do so regardless of which page a visitor is on.

A Shopify store with 15–20 apps is common. A store with 15–20 apps that all load their code on the homepage is not unusual — and it is frequently the root cause of a poor performance score.

How to identify which apps are slowing you down

Method 1: Disable apps one at a time

In Shopify admin, you can disable an app's theme extension without uninstalling the app. Disable one, run a speed check on Loadzen, note the score change. Re-enable it and disable the next. This is time-consuming but definitive.

Method 2: Check the waterfall

Open Chrome DevTools → Network tab → reload your store. Filter by domain. Every third-party domain loading resources is likely an app. Look for the size of each request.

Method 3: Check the Shopify speed score

Shopify's own speed score (in Online Store → Themes) is based on Lighthouse. It gives you a baseline and updates when you change your theme.

The apps most likely to hurt speed

Live chat: Tidio, Gorgias, Zendesk — all load heavy scripts on every page. Load these only after user interaction.

Review apps: Judge.me, Okendo, Yotpo — review widgets load JavaScript and often external fonts. Lazy load the widget on product pages rather than loading it globally.

Loyalty and rewards: Smile.io, LoyaltyLion — loads a floating widget on every page, adding a blocking script.

Upsell and cross-sell popups: These typically load entire modal frameworks on page load even before the modal is triggered.

Social proof popups: "X people are viewing this product" scripts poll servers continuously and load tracking libraries.

Apps that are typically lightweight

Metafields editors (admin-only, no storefront code)

Email marketing integrations that only add a form snippet

Shopify's own native features (Reviews, Shop Pay) are well-optimised

The rule to apply

Every app should be evaluated on the basis of: does the revenue or conversion impact of this app exceed the cost of the performance degradation it causes?

For a pop-up app that adds 2 seconds to your load time but recovers 1% more email subscribers, the maths may not work in your favour.

Run a Loadzen check before installing any new app. Run it again after installation. If the score drops by more than 5 points, evaluate carefully whether the app is worth keeping.