Image Optimization · AuditJet Glossary
Resource Preloading
An HTML link type that instructs the browser to fetch a critical resource early in the page load process before it would otherwise be discovered.
Preloading is one of the most effective LCP optimisations when the LCP element is an image. Adding <link rel=preload as=image href=hero.webp> in the HTML head tells the browser to fetch the hero image immediately — before it encounters the <img> tag. This can reduce LCP by 300–500ms on many sites. Preloading should be used selectively — preloading too many resources wastes bandwidth.
Related terms
The time from page navigation start until the largest image or text block visible in the viewport has finished rendering.
CSS and JavaScript files that prevent the browser from rendering any page content until they have been downloaded and processed.
Frequently asked questions
What is Resource Preloading?
An HTML link type that instructs the browser to fetch a critical resource early in the page load process before it would otherwise be discovered.
How does AuditJet measure Resource Preloading?
AuditJet runs automated Google Lighthouse audits that surface Resource Preloading scores alongside actionable fix guidance. You can track Resource Preloading trends across all your pages and receive alerts when the metric regresses.
Monitor Resource continuously
AuditJet tracks Core Web Vitals on a schedule with revenue impact alerts — powered by Google Lighthouse and Google PageSpeed Insights.
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