Preload Key Theme Assets improves load speed and performance by automatically preloading the essential JS, CSS and font files from your theme. It is a one-click setting that requires no theme editing.
How it works
When a browser opens your store it reads the page first, then discovers the stylesheets, scripts and fonts it needs, and only then starts downloading them. That discovery step costs time on every single visit.
Preloading removes it. The app identifies the files your theme genuinely needs to render the page and tells the browser to start fetching them straight away, in parallel with the rest of the page. Three things improve as a result:
Faster first paint — the stylesheet arrives sooner, so the page renders sooner.
Fewer font flashes — fonts arrive before the text is painted, so you avoid the flicker where text changes typeface mid-load.
Better Largest Contentful Paint — your main content becomes visible earlier, which is one of the Core Web Vitals Google measures.
Turn it on
In your Shopify admin, go to Apps → AI SEO App.
Select Preload Key (Preload Key Theme Assets) in the app menu — or open Speed Optimization and click Enable on the Preload Key Theme Assets card.
Enable the feature. The status badge at the top of the page changes to Enabled.
Check the result
Open your storefront in a new tab and reload a product page.
After a few days of real traffic, open Core Web Vitals and compare your Largest Contentful Paint value.
Good to know
The setting applies to your live theme. If you switch or heavily customize your theme, revisit this page to confirm it is still enabled.
Preloading works alongside Instant Click: preloading speeds up the first page a visitor lands on, Instant Click speeds up every page after it.
You can disable it at any time from the same screen.
New to AI SEO App? Install it from the Shopify App Store and start your 7-day free trial.