How to fix page speed warning on Klaviyo

Steps for Klaviyo

1. In your Klaviyo account, go to Settings → Integrations and locate your Klaviyo JavaScript snippet (onsite tracking). Confirm you are using the latest async/non-blocking version of the snippet — it should use 'async' or 'defer' attributes so it does not block page rendering.
2. In your storefront theme, find where the Klaviyo snippet is injected (commonly in theme.liquid or a header snippet). Move the Klaviyo <script> tag to just before the closing </body> tag rather than in the <head>, so it loads after critical above-the-fold content and does not contribute to render-blocking.
3. Remove any duplicate Klaviyo script tags across your theme files (e.g., in header.liquid, footer.liquid, and product templates). Multiple instances of the snippet multiply its load impact — only one instance should exist per page.
4. Disable any unused Klaviyo onsite features (e.g., back-in-stock, web push, signup forms) in Klaviyo → Website → Forms/Notifications. Each active feature injects additional JavaScript; disabling unused ones reduces total script payload.
5. For Klaviyo signup popup/flyout forms, go to Klaviyo → Website → Sign-up Forms, open each active form, click 'Settings', and enable the 'Show after page load delay' option (set to at least 3–5 seconds). This delays form script execution until after the main page has loaded and rendered.
6. After changes are made, test page load time using Google PageSpeed Insights or WebPageTest and confirm the Klaviyo scripts no longer appear as render-blocking resources in the diagnostics before re-publishing your theme.

What is page speed warning?

Page load time is how long it takes for a visitor's browser to fully display your store page after they click a link or type your URL. When a page takes more than 1.5–2 seconds to load, visitors experience a noticeable delay before they can see and interact with your content. A load time of 3 seconds or more (like the example finding) is considered slow by both Google and modern shoppers. Page speed is measured by several signals — the most important being Google's Core Web Vitals, which assess how fast your content appears, how quickly it becomes interactive, and how stable the layout is as it loads.

Google has officially made page speed and Core Web Vitals a direct ranking factor for all pages. Slow pages rank lower in search results, meaning fewer people find your store organically — costing you traffic and revenue before a visitor even arrives. For shoppers who do visit, studies consistently show that every additional second of load time reduces conversions: a 3-second page loses a significant portion of mobile shoppers to bounce before they see a single product. Slow stores also perform poorly in Google's mobile-first index, which evaluates your mobile experience first when deciding your rankings. Fixing page speed is one of the highest-ROI improvements an ecommerce store can make — it simultaneously boosts your SEO rankings, increases conversion rates, and improves accessibility for users on slower connections or lower-end devices.

See the complete Page speed warning guide for every platform and the full background.