A slow-loading Shopify store doesn’t just frustrate visitors—it costs sales. So as you may understand, performance is a key part of ensuring the best site rankings. And to that end, core web vitals on Shopify play a crucial role.
Core Web Vitals include Largest Contentful Paint (LCP), Interaction to Next Paint (INP), and Cumulative Layout Shift (CLS). These metrics measure loading speed, interactivity, and visual stability, shaping both user experience and search rankings.
For Shopify store owners, improving these areas can lead to better traffic, more conversions, and stronger search results. In this blog, I’ll explain how expert Shopify developers work on core web vitals to support steady growth. Let’s get straight into it.
What are Core Web Vitals?
Core Web Vitals are Google’s user-centric metrics that measure key aspects of your website’s performance. These aspects can be loading speed, interactivity, visual stability, and more. Google introduced it as a part of page experience ranking factors and directly influences SEO and user satisfaction. Here are the most important metrics to look for:
LCP – Largest Contentful Paint: Measures loading performance. A good LCP score means the main content appears quickly.
CLS – Cumulative Layout Shift: Quantifies visual stability. A high CLS score indicates annoying layout shifts while the page loads.
INP – Interaction to Next Paint: Measures how well a webpage consistently responds to user interactions.
For Shopify stores, optimizing these metrics can reduce bounce rates, boost conversions, and improve search rankings. Let’s discuss these metrics in broader detail.
What is the Largest Contentful Paint (LCP)?
Largest Contentful Paint (LCP) measures how quickly the main content of a webpage loads—what users actually see and interact with. Unlike older metrics that tracked technical loading events, LCP focuses on perceived speed. It marks the point when the largest text block, image, or video element becomes visible.
Ideal LCP Score
Good: ≤ 2.5 seconds
Needs Improvement: 2.5–4 seconds
Poor: > 4 seconds
Why LCP Matters for Shopify Stores
User Experience: Slow LCP frustrates visitors, increasing bounce rates.
Search Impact: Google prioritizes fast-loading pages in search rankings.
Conversion Rates: A 1-second delay can reduce mobile conversions by up to 20%.
What Affects LCP in Shopify Stores?
Unoptimized Images & Media: High-resolution hero images, banners, or product photos without compression.
Slow Server Response Time (Backend Delays): Hosting on an underpowered Shopify plan or third-party servers. May also be due to unoptimized Liquid code or complex theme logic.
Render-blocking Resources: JavaScript and CSS files delaying page rendering. Too many inline scripts or unminified code.
Poor CDN or Hosting Configuration: Not leveraging Shopify’s built-in CDN effectively. Third-party fonts or assets loading from slow external domains.
Large Third-party Scripts: Heavy tracking pixels (Google Analytics, Facebook Pixel). Social media embeds or review widgets are loading late.
You may consult with our experts to optimize the LCP on your Shopify store.
What is Cumulative Layout Shift (CLS)?
Cumulative Layout Shift (CLS) measures unexpected movement of visible elements while a webpage loads—like images resizing, ads popping in, or buttons shifting under a user’s finger. These abrupt jumps frustrate visitors and hurt usability.
Ideal CLS Score
Good: ≤ 0.1
Needs Improvement: 0.1–0.25
Poor: > 0.25
Why CLS Matters for Shopify Store
User Experience: 39% of shoppers abandon sites with disruptive layout shifts (Akamai).
SEO Penalty: Google downgrades pages with poor CLS in search rankings.
Lost Sales: Misclicked buttons due to shifting layouts reduce conversions.
What Affects CLS in Shopify Store?
Images/Videos Without Dimensions: Missing width and height attributes force late reflows.
Dynamically Injected Content: Banners, popups, or apps loading after the page renders.
Custom Fonts Without FOIT/FOUT Control: Text reflows when fonts finish loading.
Slow-Loading Ads or Embeds: Third-party widgets (e.g., reviews, social feeds) pushing content down.
For example, a “Buy Now” button jumps downward as a promo banner loads. It may cause accidental clicks on the wrong element.
What is Interaction to Next Paint (INP)?
Interaction to Next Paint (INP) is Google’s newest Core Web Vital metric, replacing First Input Delay (FID). It measures how quickly a webpage consistently responds to user interactions—like clicks, taps, or keystrokes. That is, by tracking the time from input to the next visual update.
Ideal INP Score
Good: ≤ 200ms
Needs Improvement: 200–500ms
Poor: > 500ms
Why INP Matters for Shopify Store
Real-World Usability: FID only measured the first delay, while INP evaluates all interactions (e.g., filtering products, adding to cart).
Mobile Impact: Slow INP frustrates users on low-powered devices, increasing bounce rates.
SEO & Conversions: Google uses INP as a ranking factor, and delays during checkout can abandon carts.
What Affects INP in Shopify Stores?
Heavy JavaScript Execution: Apps/widgets running long tasks (e.g., live chat, analytics). Unoptimized theme code is blocking the main thread.
Too Many Third-Party Scripts: Social media embeds, ad trackers, or review tools loading late.
Unoptimized “Hydration” (For React-based Themes): Excessive client-side processing in themes like Dawn.
For example, a customer taps “Add to Cart”. But nothing happens for 2 seconds because a script is processing in the background.
If you need help with these factors, consult with our Shopify development company. Our team understands the significance of Google search ranking factors, especially CWV.
Google’s Core Web Vitals (primarily LCP, CLS and INP) directly impact your store’s user experience and search rankings.
Largest Contentful Paint
The goal with this optimization is to ensure the largest visible element (like hero image, heading, video, etc.) loads in under 2.5s.
Compress & Lazy Load Images
Large, unoptimized images are the top culprit for slow LCP. Use Shopify’s built-in image compression or tools like TinyPNG. It can help reduce file sizes without sacrificing quality.
Implement lazy loading so images only render when they enter the viewport, prioritizing above-the-fold content. Formats like WebP can cut load times by 30% compared to JPEG/PNG.
Upgrade to a Faster Theme
Outdated or bloated themes drag down LCP. Switch to lightweight, performance-optimized themes like Dawn (Shopify’s default) or Impulse. Avoid excessive animations, complex widgets, and unnecessary scripts. Test themes using Google PageSpeed Insights before committing.
You can also consult with our experts to build a custom theme for your Shopify store.
Reduce Server Response Time
Slow server responses delay LCP. Upgrade to Shopify Plus for faster infrastructure, or minimize app bloat that adds backend processing. Use a global CDN (like Shopify’s) to reduce latency. Monitor TTFB (Time to First Byte) and aim for under 500ms.
Eliminate Render-blocking Resources
JavaScript and CSS files can block page rendering. Defer non-critical scripts, inline critical CSS, and minify code. Shopify’s theme editor lets you conditionally load scripts. Tools like Critical CSS Generator help prioritize visible content.
Cumulative Layout Shift (CLS)
The goal with this optimization is to keep CLS below 0.1 to prevent elements from jumping around.
Set Explicit Dimensions for Media
Always define width and height attributes for images, videos, and banners. This reserves space during loading, preventing sudden jumps. Use CSS aspect ratio boxes for responsive designs. Shopify’s image_tag filter auto-injects dimensions—leverage it.
Reserve Space for Dynamic Content
Banners, pop ups, or app widgets that load late cause layout shifts. Pre-allocate space with placeholder divs or CSS min-height. For Shopify’s announcement bar, hardcode its height in theme settings to avoid header reflow.
Optimize Fonts & Web Fonts
Custom fonts triggering FOIT/FOUT (Flash of Invisible/Unstyled Text) increase CLS. Use font-display: swap in CSS, or host fonts locally instead of relying on Google Fonts. Limit font weights to 2-3 variants.
Test Third-Party Embeds
Social feeds, reviews, or ads often load unpredictably. Load them asynchronously or after page render. For Shopify apps like Loox or Judge.me, test their CLS impact using Chrome DevTools’ Performance tab.
For Interactivity to Next Paint (INP)
The goal with this optimization is to achieve INP under 200ms for instant responses.
Minimize Long JavaScript Tasks
INP suffers when JavaScript monopolizes the main thread. Break up heavy scripts into smaller chunks using setTimeout or requestIdleCallback. Audit Shopify apps—disable or delay non-essential ones (e.g., post-purchase upsell tools).
Use Web Workers for Background Tasks
Offload intensive operations (e.g., cart calculations, analytics) to Web Workers. Shopify’s Hydrogen framework supports this for React-based themes. Keeps the main thread free for user interactions.
Optimize Shopify’s “Liquid” Code
Poorly structured Liquid templates can delay interactivity. Avoid nested loops, excessive if conditions, and complex filters. Pre-compute data where possible using metafields or Shopify Functions.
Reduce Third-party Script Impact
Tools like Google Analytics, Meta Pixel, or Hotjar can lag INP. Load them asynchronously, use lighter alternatives (e.g., Partytown), or delay until user interaction (e.g., scroll). Shopify’s script manager helps prioritize critical resources.
Among these CWV factors, LCP has the biggest impact on the user and search experience. Then you may go about refining the CLS and INP.
Tools for Core Web Vitals for Shopify
To improve LCP, INP, and CLS, you need the right tools for tracking, diagnosing, and fixing performance issues. Let’s take a look at these one-by-one.
Best for: Quick, actionable Core Web Vitals reports
PageSpeed Insights analyzes your Shopify store’s LCP, INP, and CLS with real-world (CrUX) and lab data. Simply enter your URL to get a detailed breakdown of performance issues, optimization suggestions, and mobile/desktop scores—all for free.
Best for: Monitoring real-user Core Web Vitals over time
Google Search Console’s Core Web Vitals report shows how your Shopify store performs for actual visitors. Track LCP, INP, and CLS trends, identify problematic pages, and validate fixes—directly tied to your search rankings.
Best for: Technical debugging & development testing
Run Lighthouse (in Chrome DevTools) for lab-based Core Web Vitals audits. It simulates mobile/desktop loads, flags render-blocking resources, and provides step-by-step fixes for JavaScript, CSS, and image optimizations.
Dynatrace auto-detects Core Web Vitals regressions in Shopify stores, linking them to specific apps, scripts, or hosting issues. Its session replays show exactly how delays impact user behavior.
You can identify the issues with Google PageSpeed while following the search trends with Google Search Console. And for further help with how these tools and strategies will work in your favor, get our eCommerce consulting services.
FAQs on Core Web Vitals for Shopify
How can I reduce CLS (layout shifts) in Shopify?
Set explicit image dimensions, avoid dynamically injected content (e.g., popups), and preload fonts to prevent unexpected page jumps.
Do Shopify themes affect Core Web Vitals?
Yes. Lightweight themes (like Dawn) perform better. Avoid bloated themes with excessive JavaScript or complex Liquid code.
Can apps hurt my Core Web Vitals?
Absolutely. Poorly coded apps add unnecessary scripts. Regularly audit and remove unused apps, or delay their loading.
Does Shopify’s CDN help with Core Web Vitals?
Yes, it improves LCP by caching content globally. Ensure images and assets leverage Shopify’s built-in CDN.
Are Core Web Vitals more important for mobile?
Yes. Google uses mobile-first indexing, and slow mobile performance hurts rankings and UX more significantly.
Let’s Summarize
Optimizing Core Web Vitals isn’t just about pleasing Google—it’s about creating a seamless experience for your customers. Faster load times, smoother interactions, and stable layouts keep shoppers engaged. It can reduce frustration and ultimately drive more sales.
Optimizing CWV involves technical improvements like image optimization, script management, and theme tweaks, among others. While they may seem small, their collective impact is undeniable. Start with LCP and CLS, which are bigger issues, then test changes and monitor progress.
Remember, a fast store is a high-converting store. So if you want more help with it, connect with us today!
John Niles, a dedicated Technical Consultant at BrainSpate since 2023, specializes in eCommerce. With a global perspective, he crafts insightful content on cutting-edge web development technologies, enriching the digital commerce landscape.
