How to fix slow page on Klaviyo

Steps for Klaviyo

1. In your Klaviyo account, go to Settings → Integrations and confirm you are using the latest version of the Klaviyo JavaScript snippet (klaviyo.js). Older embed methods load synchronously and block rendering.
2. Replace any legacy synchronous embed (e.g. a <script> tag without async/defer in your theme's <head>) with Klaviyo's recommended asynchronous snippet. In Shopify, navigate to Online Store → Themes → Edit Code → theme.liquid and ensure the Klaviyo <script> tag includes the 'async' attribute: <script async type='text/javascript' src='https://static.klaviyo.com/onsite/js/klaviyo.js?company_id=XXXXXX'></script>
3. Audit active Klaviyo on-site forms (pop-ups, flyouts, banners) in Klaviyo → Forms. Disable or archive any forms that are not currently running campaigns — each active form adds JavaScript evaluation weight on every page load.
4. For forms that must stay active, set their display trigger to a time delay (e.g. 5 seconds) or scroll depth (e.g. 40%) rather than 'Immediately on page load'. This defers Klaviyo form rendering until after the critical rendering path is complete.
5. Turn off Klaviyo's A/B testing on forms if not actively needed. Multiple test variants cause the snippet to fetch additional assets on load; disabling unused tests in Klaviyo → Forms → [Form] → A/B Test reduces this overhead.
6. After making changes, validate page speed improvement using Google PageSpeed Insights or WebPageTest and confirm the Klaviyo script no longer appears as a render-blocking resource in the waterfall chart.

What is slow page?

Page load time is how long it takes for a visitor's browser to fully display your store page. When a page takes longer than about 3 seconds, visitors tend to leave before they even see your products — a behaviour called "bouncing." Google also directly measures loading speed as part of its Core Web Vitals scoring system, which feeds into how high your pages rank in search results. A load time of nearly 10 seconds (like the example above) is extremely slow and will hurt both rankings and sales.

Google uses Core Web Vitals — which include Largest Contentful Paint (LCP), a direct measure of loading speed — as a confirmed ranking signal. Pages that load slowly rank lower in search results, meaning fewer shoppers find you organically. Research consistently shows that every additional second of load time reduces conversion rates by roughly 4–7 %, so a 10-second page can cost you a significant share of potential sales. Slow pages also create a poor first impression, increase bounce rates, and can disqualify your pages from Google's "Page Experience" enhancements in search results. On mobile — where Google primarily indexes your site — performance issues are amplified further.

See the complete Slow page guide for every platform and the full background.