App Speed Report · Updated March 2026
Does Postscript Slow Down Your Shopify Store?
Speed impact analysis of Postscript (SMS Marketing) — how much it affects your page load time, what scripts it loads, and how to mitigate the performance cost.
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Postscript Speed Impact Summary
2
Scripts Loaded
85KB
Total Script Size
100-200ms
Avg. Load Time Impact
App Name
Postscript
Category
SMS Marketing
Impact Level
Low
How Postscript Affects Your Store Speed
Postscript is an SMS marketing platform with popup opt-in forms and subscriber tracking. Its storefront footprint is limited to the opt-in widget and tracking pixel.
When a visitor lands on your store, Postscript loads 2 JavaScript files totaling approximately 85KB. 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 100-200ms 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 Postscript adds 100-200ms to your page load, that's a measurable impact on your bottom line.
Postscript 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 Postscript.
What These Scripts Do
Postscript's scripts handle its core sms marketing functionality on your storefront. This typically includes:
- • Core functionality script — The main JavaScript bundle that powers Postscript's features on your pages
- • Tracking/analytics script — Monitors user interactions and behavior for Postscript's dashboard and reporting
The problem isn't that these scripts exist — it's that they often load synchronously and on every page, even pages where Postscript's functionality isn't needed. A visitor browsing your blog doesn't need Postscript's full sms marketing scripts loading and executing.
How to Reduce Postscript's Speed Impact
You don't have to choose between Postscript's functionality and a fast store. Here's how to minimize its performance impact while keeping the features you need:
Postscript's impact is relatively low — prioritize heavier apps for optimization
Disable the popup opt-in on pages where it interrupts the purchase flow
Use time-delayed triggers for the SMS popup to improve perceived performance
Remove the tracking pixel from pages where you don't need behavioral data
Consolidate SMS tools — don't run Postscript alongside SMSBump or Attentive simultaneously
🔍 SEO impact: Reducing Postscript'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 Postscript
Complete these steps to minimize Postscript's speed impact
The Bigger Picture: App Bloat on Shopify
Postscript 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 Postscript adds 100-200ms 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 Postscript), and optimizes how they all load — deferring non-essential scripts, reducing blocking time, and ensuring your critical page content loads first.
⚡ See How Postscript Affects Your Store
Thunder scans your installed apps — including Postscript — 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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Frequently Asked Questions
Does Postscript slow down Shopify stores?
Postscript has a low speed impact on Shopify stores, typically adding 100-200ms to page load time. It loads 2 scripts totaling approximately 85KB. 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 Postscript affect my PageSpeed score?
Postscript typically reduces your PageSpeed Insights mobile score by 3-5 points depending on your store's baseline performance and other installed apps. The 85KB 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 Postscript to improve speed?
Not necessarily. Postscript provides valuable functionality (sms marketing) 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 Postscript and still have a fast Shopify store?
Yes. Many high-performing Shopify stores use Postscript successfully. The key is optimization: don't load Postscript'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 Postscript's JavaScript until after your critical content has loaded. A well-optimized store with Postscript can still score 80+ on PageSpeed mobile.
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