How to find which Shopify app is slowing your store

Most Shopify stores have more apps than their owners can list from memory. Each can add scripts and styles to your pages, and together they are frequently the largest single cause of a slow store. The difficulty is that the damage is spread out, so no one app looks guilty.

Here is a method that finds them without risking the live store.

Step 1: list what loads

Open your product page in Chrome, open DevTools, go to the Network tab and reload. Sort by size, then filter by JS. Look at the domain of each script. Anything that is not your own store or Shopify belongs to an app or a service: reviews, chat, pop-ups, analytics, currency, loyalty.

Write down every third-party domain. Then match each to a purpose. Some will surprise you.

Step 2: look at the main thread

In the Performance tab or in PageSpeed Insights, find the diagnostic that lists scripts by the time they spend running. Third-party scripts with long execution times are the first suspects, because they block the page from responding to taps.

Step 3: duplicate the theme and test

In the admin, go to Online Store, then Themes, and duplicate your live theme. Never experiment on the live one.

In the copy:

1. Remove one app's code, either by turning off its app embed in the theme editor or by deleting its snippet.
2. Preview the copy on the same page.
3. Run PageSpeed Insights on the preview URL.
4. Write down the change in LCP and Total Blocking Time.

Repeat for the next app. After five or six rounds, a ranking appears. In most stores one or two apps account for most of the cost.

Step 4: decide what each app earns

For each heavy app, ask what it contributes. A reviews widget that produces trust on product pages usually earns its weight. A pop-up that fires on every page and converts rarely does not. Where an app is worth keeping, check whether it offers a lighter loading option, such as loading only on the pages that use it.

Step 5: clean up leftovers

Removing an app from the admin does not always remove its code. Search your theme files for the names of apps you no longer use. Common places are theme.liquid, the snippets folder, and assets. Take a backup before deleting anything. If you are unsure, ask a developer to review the list, a short job.

Keep it that way

Before installing any new app, test the page speed with and without it on a duplicate theme. That habit takes ten minutes and stops the problem coming back.

An audit lists the third-party scripts your pages load and attributes slow files to the app or theme that serves them, which gives you the Step 1 and Step 2 list in one place.