How to Audit Shopify App Performance

Why Apps Slow You Down

Every Shopify app that adds a frontend component loads additional resources on your pages. A review app loads its widget JavaScript. A chat app loads its SDK. A loyalty programme loads its points display. These all add up.

A single app might add 100-300KB of JavaScript and make 5-10 additional network requests. With 10 apps installed, that is potentially 3MB of additional JavaScript and 100 extra network requests on every page load.

Many apps also inject scripts into all pages, even when they are only needed on specific pages. A checkout upsell app that loads its scripts on the homepage serves no purpose and just wastes bandwidth.

Identifying Problem Apps

Run your store through PageSpeed Insights and look at the Render Blocking Resources and Unused JavaScript sections. These often list scripts by domain. Third-party domains (not your store's domain) are typically app scripts.

Cross-reference the domains listed against your installed apps. Most app scripts load from a CDN with a domain related to the app name. For example, Klaviyo loads from klaviyo.com, Yotpo from yotpo.com.

Using DevTools and Tag Assistant

Open Chrome DevTools and go to the Network tab. Filter by "Other" or "Script" and reload the page. Look for any scripts loading from unfamiliar third-party domains.

The Performance tab in DevTools gives a flame chart showing exactly when each script executes and how long it blocks the main thread. Scripts with long main thread blocking times are your primary targets.

Measuring App Impact

To accurately measure an individual app's impact, run a PageSpeed test with the app enabled, then disable the app and run the same test. The difference shows you exactly how much the app costs in performance terms.

Some apps have a "disable on storefront" option. Others require uninstallation to fully remove their scripts. For testing purposes, you can temporarily comment out the app embed in your theme without fully uninstalling.

Removing Apps Cleanly

When you uninstall a Shopify app, the app's code injected into your theme.liquid does not always get removed. After uninstalling, check theme.liquid, head.liquid, and footer.liquid for orphaned script tags or stylesheet links.

Also check the App Embeds section in your theme editor. Disabled embeds from uninstalled apps can still leave empty placeholders. Remove these and save your theme.

App Alternatives

For apps you need but that are slow, look for alternatives with smaller footprints. Many app categories have lightweight challengers to the established players.