Shopify apps can slow your store down. Shopify names the apps you’ve installed as one of the biggest factors in store speed, because many load scripts and styles on your storefront, and some leave code in your theme after you uninstall them. Check the web performance report for slowdowns after app installs, test one app at a time, and keep only the apps that earn more than they cost in speed.
How do apps add weight to a Shopify store?
Most apps that show something to shoppers, such as reviews, chat, pop-ups, upsells, size charts or tracking pixels, need code that runs in the shopper’s browser. That means extra JavaScript, CSS, fonts or images that a phone has to download and run before the page feels ready. Shopify’s own guide to improving store performance names two factors as the biggest: your theme and the apps you’ve installed.
Each app adds a little. Shopify says that if your store has a poor Interaction to Next Paint score, the most likely cause is too much JavaScript from theme code, app code, or third-party or tag manager code. So the question for Shopify apps slowing your store is rarely “which one app is the problem?” and more often “what is the total, and which apps are worth their share?”
App blocks and app embeds vs code in your theme files
How an app puts its code into your store matters for speed today and for cleanup later. There are two ways:
- App blocks and app embeds, built with Shopify’s theme app extensions. An app block sits exactly where you place it on a page, such as reviews under the product description. An app embed floats or shows as an overlay, such as a chat bubble. Both can be added, removed or switched off in the theme editor, and apps built this way don’t edit your theme code.
- Code added to theme files. Shopify’s help notes that some apps inject code directly into your theme’s code, and some ask you to paste a snippet into the theme during setup. That code lives in your theme, not in the app, which is what causes leftovers later.
To earn Shopify’s Built for Shopify status, an app has to use theme app extensions instead of editing theme files, and must not reduce the storefront Lighthouse performance score by more than ten points. That is a limit per app, so several apps that each stay within it can still add up to a slow store.
How do I find which app is slowing my store?
Start with Shopify’s data, then list what each app loads, then test pages one by one. A Shopify store audit covers the same ground: its speed check on mobile includes the scripts each app adds.
1. Read the web performance report
In your Shopify admin, go to Analytics > Reports and open the web performance reports. They show Largest Contentful Paint, Interaction to Next Paint and Cumulative Layout Shift from real visitors over the past 30 days, each rated Good, Moderate or Poor. The over-time chart marks changes such as app installations, theme updates and new code as numbered lines; hover over one to see what changed. If a score got worse right after an app went in, that app is your first suspect.
The Page URL and page type views show whether the problem is on every page or only some. A slowdown only on product pages points at apps that load there, such as reviews, upsells or size charts. Keep the limits in mind: Shopify says the data can be delayed by up to 36 hours, covers only the last 90 days, and may be missing if your store is new or in private mode.
2. List what each app loads
Open your live theme in the theme editor and click the App embeds icon in the sidebar to see which embeds are switched on. Then go through the home, collection, product and cart templates and note the app blocks on each. Compare that list with your installed apps under Settings > Apps. An app that shows on the storefront but has nothing in the theme editor is probably adding code to your theme files.
3. Test key pages in PageSpeed Insights
Shopify suggests running your own reports in Google’s PageSpeed Insights for more detail. PageSpeed Insights shows two kinds of data: field data from real Chrome users over the previous 28 days, and a lab test run by Lighthouse in a simulated environment. Google notes that lab data is useful for debugging because it is collected in a controlled environment, so use the lab test for your before-and-after checks. Test the home page, a busy collection and a best-selling product page, on mobile.
If a page sits blank and then loads all at once, Shopify suggests using your browser’s developer tools to find the slow-loading scripts and contacting the app or theme developer about them. Script file names and web addresses often include the app’s name or its developer’s domain, which tells you whose code it is. For causes that have nothing to do with apps, such as oversized images or slow hosting, see our guide to why a website is slow.
Does uninstalling an app remove its code?
It depends on how the app added it.
- App blocks and app embeds from theme app extensions go when the app goes. Shopify’s developer documentation says that when merchants uninstall apps, the blocks associated with them are automatically and entirely removed from online store themes.
- Code in theme files may stay. Shopify’s help says some apps add code to your theme that isn’t automatically removed when you uninstall the app, and that you might need to contact the developer for complete removal instructions.
Leftover code can keep loading files on every page for an app you no longer use. Here is how to check for it and remove it safely:
- Before you uninstall, check the app’s listing or ask the developer whether removal needs extra steps. In your admin, Settings > Apps > Get support reaches the developer. Export any data you want to keep.
- Duplicate your theme. Shopify’s advice is to make a duplicate before you delete any theme file, so you can go back.
- Search the theme code. Open Edit code on your theme and use the search in the left sidebar to search across all theme files for the app’s name, its developer’s domain or the snippet name from its setup instructions. Check the main layout file and the snippets folder.
- Remove only code you can tie to the app. Shopify warns that deleting a theme file might break your theme and that deleted files can’t be recovered. The Timeline view can restore an earlier version of a file you edited, one file at a time, but its history is limited.
- Test the store: product pages, cart and a checkout on phone and desktop.
If you aren’t sure a piece of code belongs to the app you removed, leave it and ask the developer. Deleting the wrong snippet from a live theme causes more trouble than one extra script.
How do I test before and after removing an app?
Change one thing at a time. If you remove four apps at once and the store gets faster, you won’t know which one mattered, or whether you gave up a feature that was selling for nothing.
- Duplicate the live theme, so you have a backup to return to.
- Record a baseline: the current web performance scores, and PageSpeed Insights lab results for the same three pages on mobile. Google notes that results vary from run to run, so run each test three times and keep the middle result.
- At a quiet time of day, switch off one app embed or remove one app block in the theme editor. You can turn the embed back on, or add the block again, from the same place.
- Run the same tests on the same pages and compare.
- Check what shoppers lose: does the page still work, and do reviews, size guides or delivery messages disappear?
- Decide: switch it back on, replace it with something lighter, or uninstall it and clean up any leftover code.
- Repeat for the next app. After the changes are final, watch the web performance report over the following weeks. It is based on 30 days of real visits and may lag by up to 36 hours, so it won’t move straight away.
Which Shopify apps are worth keeping?
Speed is one side of the trade. Shopify’s advice is to check that installed apps create enough value to offset their performance cost, and to remove any that aren’t essential for sales. Use the app’s own reports and your sales data, not a guess:
| What the app does | Check | Usually |
|---|---|---|
| Product reviews and ratings | Do shoppers read them, and does the app load only where reviews show? | Keep; place it only on the pages that need it |
| Live chat or chatbot | How many chats a month answer pre-sale questions or lead to orders? | Keep if it is used; remove if chats are rare |
| Pop-ups and email capture | Sign-ups per month, and whether two apps do the same job | Keep one; remove duplicates |
| Upsells and cross-sells | Orders that include the offer, in the app’s own report | Keep if the extra order value shows; otherwise remove |
| Tracking pixels and analytics | Is the same pixel loaded by an app and by theme code? | Keep one copy; remove the duplicate |
| Page builders | Do your live pages still use it? | Replace with theme sections where the theme can do the same |
| Badges, size charts, announcement bars | Does your theme already offer this as a section or setting? | Replace with the theme feature |
| Apps you stopped using | Is any of its code still in the theme editor or theme files? | Remove, then clean up leftover code |
When you choose a new app, prefer one that works through app blocks or app embeds, because you can switch it off in the theme editor and it is removed when you uninstall. Ask the developer whether the app has Built for Shopify status, and test your key pages before and after you install it.
If a feature matters to your sales but every app for it is heavy, it can be cheaper in speed to build it into the theme once. That is theme work our Shopify and e-commerce team does. If the store is slow and also not converting, work through our guide to Shopify traffic but no sales as well.
Want someone to check your apps for you? Send your store URL for a free website audit. For stores, we look at speed on mobile, the apps loaded on each page, product pages and checkout, and tell you what to fix first.
Frequently asked questions
How many Shopify apps is too many?
There is no safe number, and Shopify’s performance guidance doesn’t give one. It says too many apps loading assets on your storefront can slow performance. One app that loads heavy scripts on every page can cost more speed than several apps that only work in your admin. Judge each app by what it loads and what it earns, and check your web performance report after every install.
Does uninstalling an app remove its code?
Not always. App blocks and app embeds built with Shopify’s theme app extensions are removed automatically when you uninstall the app. Code an app wrote into your theme files, or that you pasted in during setup, can stay behind. Ask the developer for removal steps before you uninstall, duplicate your theme, then search the theme code for the app’s name.
Will removing apps break my theme?
Uninstalling an app usually just removes its feature, such as the reviews or the chat bubble. The risk is in deleting leftover code by hand: Shopify warns that deleting a theme file might break your theme, and deleted files can’t be recovered. Duplicate the theme first, remove one app at a time, and test product pages, cart and checkout after each change.
Sources
- Shopify Help Center: improving your online store performance
- Shopify Help Center: web performance reports
- Shopify Help Center: uninstalling apps
- Shopify Help Center: extend your theme with apps (app blocks and app embeds)
- Shopify Help Center: editing theme code
- Shopify.dev: Built for Shopify requirements (store speed and clean uninstall)
- Google for Developers: about PageSpeed Insights (lab and field data)