App Speed Report · Updated March 2026
Does Back in Stock Slow Down Your Shopify Store?
Speed impact analysis of Back in Stock (Inventory Alerts) — how much it affects your page load time, what scripts it loads, and how to mitigate the performance cost.
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Back in Stock Speed Impact Summary
1
Scripts Loaded
40KB
Total Script Size
50-120ms
Avg. Load Time Impact
App Name
Back in Stock
Category
Inventory Alerts
Impact Level
Low
How Back in Stock Affects Your Store Speed
Back in Stock adds notification signup forms on out-of-stock product pages. Its script only activates when a product variant is unavailable.
When a visitor lands on your store, Back in Stock loads 1 JavaScript file totaling approximately 40KB. These scripts need to be downloaded, parsed, and executed by the browser — all of which takes time and competes with your core page content for network bandwidth and CPU resources.
The measured impact is 50-120ms of additional page load time. To put that in perspective: Google research shows that each additional 100ms of load time reduces conversion rates by up to 7%. If Back in Stock adds 50-120ms to your page load, that's a measurable impact on your bottom line.
Back in Stock has a relatively low speed impact compared to other Shopify apps. If you're looking to improve speed, focus on higher-impact apps first before optimizing Back in Stock.
What These Scripts Do
Back in Stock's scripts handle its core inventory alerts functionality on your storefront. This typically includes:
- • Core functionality script — The main JavaScript bundle that powers Back in Stock's features on your pages
The problem isn't that these scripts exist — it's that they often load synchronously and on every page, even pages where Back in Stock's functionality isn't needed. A visitor browsing your blog doesn't need Back in Stock's full inventory alerts scripts loading and executing.
How to Reduce Back in Stock's Speed Impact
You don't have to choose between Back in Stock's functionality and a fast store. Here's how to minimize its performance impact while keeping the features you need:
Back in Stock has minimal impact — its script only runs on out-of-stock products
Verify the script isn't loading on in-stock product pages unnecessarily
Ensure the app doesn't inject scripts on collection or homepage pages
Use the app's built-in form styling to avoid loading additional CSS files
Back in Stock is a low-priority optimization target — focus on heavier apps first
🔍 SEO impact: Reducing Back in Stock's speed impact helps your store pass Core Web Vitals — Google's official ranking signal since 2021. Better speed = higher rankings = more organic traffic.
Quick Optimization Checklist for Back in Stock
Complete these steps to minimize Back in Stock's speed impact
The Bigger Picture: App Bloat on Shopify
Back in Stock is just one app on your store. The average Shopify store has 15-25 apps installed, and each one adds its own JavaScript and CSS to your storefront. The cumulative effect is what really kills your speed score.
Think about it: if Back in Stock adds 50-120ms and you have 10+ other apps each adding 100-400ms, your total third-party script overhead could be 2-5 seconds. That's the difference between a store that converts and one that loses visitors before the page even loads.
Manually optimizing each app's loading behavior is time-consuming and requires technical knowledge. You'd need to edit theme files, understand JavaScript loading patterns, and constantly monitor for regressions when apps update their scripts.
This is exactly the problem Thunder was built to solve. Thunder automatically scans every app on your store, measures each one's actual speed impact (including Back in Stock), and optimizes how they all load — deferring non-essential scripts, reducing blocking time, and ensuring your critical page content loads first.
⚡ See How Back in Stock Affects Your Store
Thunder scans your installed apps — including Back in Stock — and shows you exactly how much each one impacts your speed. Then it fixes them automatically.
Install Thunder Free →Free plan available · Scans all your apps · No code changes required
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Health & Beauty
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Home & Garden
Frequently Asked Questions
Does Back in Stock slow down Shopify stores?
Back in Stock has a low speed impact on Shopify stores, typically adding 50-120ms to page load time. It loads 1 script totaling approximately 40KB. While this isn't negligible, you can mitigate the impact by deferring its scripts, limiting which pages it loads on, and using a speed optimization app like Thunder to manage its loading behavior.
How much does Back in Stock affect my PageSpeed score?
Back in Stock typically reduces your PageSpeed Insights mobile score by 3-5 points depending on your store's baseline performance and other installed apps. The 40KB of JavaScript it loads contributes to longer Time to Interactive (TTI) and potentially affects Largest Contentful Paint (LCP) if scripts block rendering. The actual impact varies — stores with fewer apps will notice it more.
Should I uninstall Back in Stock to improve speed?
Not necessarily. Back in Stock provides valuable functionality (inventory alerts) that likely benefits your store. Instead of uninstalling, optimize how it loads: defer non-critical scripts, limit it to pages where it's needed, and use Thunder to automatically manage its loading priority. Only uninstall if you're not actively using the app or if the speed cost outweighs the business value.
Can I use Back in Stock and still have a fast Shopify store?
Yes. Many high-performing Shopify stores use Back in Stock successfully. The key is optimization: don't load Back in Stock's scripts on pages where they're not needed, compress your images to offset the script overhead, and use a tool like Thunder to defer Back in Stock's JavaScript until after your critical content has loaded. A well-optimized store with Back in Stock can still score 80+ on PageSpeed mobile.
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