When someone asks us "why is my Shopify store so slow?", the honest first answer is a question back: how many apps do you have installed — and how many did you used to have?
That second part surprises people. You'd expect an uninstalled app to be gone. On Shopify, it often isn't. The visible app disappears from your admin, but the code it injected into your theme can stay right where it was, still loading on every page. We've opened stores where a third of the third-party JavaScript belonged to apps the owner was certain they'd removed months ago.
As a Shopify Plus Partner, we've audited 40+ stores, and app-related bloat is the most common speed problem we find not the theme. Across those audits, a typical store is carrying 10–15 unnecessary app and third-party scripts, some of them orphaned from apps that are no longer even active. If your store feels sluggish on mobile, this is where to look first. (If you'd rather see it scored for you, our free Shopify audit flags third-party scripts and Core Web Vitals automatically.)
App count is the wrong thing to measure
The usual advice "you have too many apps" isn't quite right. App count on its own is misleading. Five heavy apps can hurt your store more than twenty-five lightweight ones. We've seen lean stores with 20+ apps load fine, and bloated stores with 8 apps crawl.
What actually matters is what each app does on the page: how much JavaScript it runs, whether it blocks rendering, how many extra requests it fires, and crucially whether it loads on pages where it isn't even needed. A review widget has no business executing JavaScript on your checkout. A bundle app doesn't need to run on your blog.
So the better questions are: which scripts run on every page? How much of that JavaScript is actually used? And how much of it belongs to something you still use? That said, here's a practical line in the sand from doing this a lot: once a Shopify store gets past about 15–20 apps, it has earned a serious speed audit not because the number is magic, but because that's where the "loads on every page" problem usually compounds.
The biggest issue is usually not the apps merchants can see. It's the code they thought they removed still loading on every page, months after the app was uninstalled.
The usual suspects
Some categories of app are repeat offenders. Individually, most are fine. The damage happens when several of them all load JavaScript on every page, whether that page needs them or not. These are the ones we see slowing stores most often:
- Review widgets often load star ratings and scripts site-wide, including on pages with no reviews.
- Popups and email capture frequently render-blocking and triggered on load.
- Upsell and bundle apps inject cart and product logic across the whole store.
- Live chat one of the heaviest single third-party scripts you can add.
- Loyalty and rewards widgets and balances that load everywhere.
- Personalization tools run JavaScript early to swap content, delaying paint.
- Session recording and heatmaps valuable for research, costly left running permanently.
- Duplicated tracking pixels the same analytics or ad pixel firing twice because it's installed via an app and hard-coded in the theme.
None of these is a reason to panic. The point of an audit is to decide, for each one, whether it earns its place and whether it can be loaded only where it's actually used instead of everywhere.
The hidden killer: code you already "removed"
Here's our strongest take, and the thing most speed guides miss. The worst offender usually isn't an app you can see in your admin. It's the leftover code from apps you uninstalled.
On Shopify, apps rarely live in one tidy place. To work, many of them inject snippets into your theme into theme.liquid, section files, or as custom Liquid register script tags that load on every page, and sometimes add lines into your checkout or "additional scripts." When you uninstall the app, Shopify removes the app. It does not reliably remove everything the app left behind. The visible part is gone; the scripts and snippets can keep loading.
Multiply that across a store that's tried a dozen apps over two years a different review app, two abandoned popup tools, an old chat widget and you get a theme quietly loading scripts for half a dozen things that no longer exist. Your admin looks clean. Your storefront is dragging a graveyard behind it.
This is exactly why "I uninstalled some apps and it's still slow" is such a common complaint. Uninstalling removes the app. It often doesn't remove the weight.
What a cleanup actually looks like
The good news: because so much of this is dead weight, removing it is low-risk and high-impact. In one typical cleanup, stripping out around 11 unnecessary app and script loads a mix of orphaned code and apps that loaded everywhere made the storefront substantially faster without touching the theme design at all.
Across our audits, that kind of work tends to move mobile Largest Contentful Paint from 4+ seconds down to roughly 2–2.5 seconds, with noticeably lower blocking time. Lower blocking time matters more than ever now that Interaction to Next Paint (INP) is a Core Web Vital heavy third-party JavaScript is one of the main reasons a store feels laggy to tap and scroll, and apps are usually where that JavaScript comes from. We go deeper on the vitals themselves in why half of Shopify stores fail Core Web Vitals on mobile.
How to find what's really loading
You don't have to guess. Here's how to see the truth:
- Run PageSpeed Insights on your homepage, a collection and a product page (test mobile). Look at "Reduce unused JavaScript" and "Reduce the impact of third-party code."
- Use Chrome DevTools the Coverage tab shows how much of each script is actually used, and the Network tab shows every third-party request and who it belongs to.
- Cross-check against your installed apps. Any script that doesn't map to an app you currently use is a candidate for removal that's your leftover code.
- Check the hiding spots:
theme.liquidand section files for injected snippets, your theme's asset files, registered script tags, and your checkout / additional scripts. - Consolidate tracking into a single tag manager instead of a pixel per app, and remove duplicates.
If you'd rather start with a scorecard than a DevTools session, our free Shopify store audit checks third-party scripts, render-blocking resources and Core Web Vitals and tells you what to fix first no Shopify login required. And once speed is handled, it's worth running the full Shopify SEO audit checklist, since page speed and crawlability feed each other.
The takeaway is simple: before you blame your theme or your hosting, look at what your apps are loading including the ones you're sure you already deleted. Most "slow Shopify store" problems are hiding there.