Website Speed Audit Checklist

How the Website Speed Audit Checklist Works

This interactive audit evaluates your website against 26 proven performance optimizations grouped into six key areas: image optimization, font loading, JavaScript efficiency, CSS delivery, caching and CDN configuration, and Core Web Vitals compliance. Each item carries a weighted score based on its real-world impact on page load times. As you check off implemented optimizations, your score updates in real time with a letter grade from A+ down to F.

The audit is weighted so that the highest-impact areas — images, JavaScript, and Core Web Vitals — carry the most points. A score of 90 or above earns an A+, meaning your site follows industry best practices. Below 50 signals critical performance gaps that hurt user experience and SEO rankings.

Why Website Speed Matters for SEO

Google uses Core Web Vitals as a ranking signal. Largest Contentful Paint (LCP), Interaction to Next Paint (INP), and Cumulative Layout Shift (CLS) directly affect your search visibility. Pages that load in under 2.5 seconds have significantly lower bounce rates and higher conversion rates. Studies show that a one-second delay in page load time can reduce conversions by up to 7 percent. This checklist ensures you cover every optimization that contributes to faster load times and better search rankings.

Image and Font Optimization Best Practices

Images typically account for over 50 percent of a page's total weight. Converting to modern formats like WebP or AVIF can reduce file sizes by 25 to 50 percent compared to JPEG. Lazy loading defers off-screen images, cutting initial payload. Responsive images with srcset serve appropriately sized files to each device. For fonts, WOFF2 compression reduces font file sizes by 30 percent over WOFF. The font-display swap property prevents invisible text during loading, and subsetting removes unused characters to minimize download size.

JavaScript, CSS, and Caching Strategies

Render-blocking JavaScript is the leading cause of slow Time to Interactive. Code splitting ensures users download only the code they need. Moving analytics to a web worker with tools like Partytown eliminates main-thread overhead. On the CSS side, inlining critical above-the-fold styles prevents layout shifts, while removing unused CSS reduces payload. A properly configured CDN with Cache-Control headers and Brotli compression can cut Time to First Byte by over 60 percent. Combining these strategies with a service worker enables offline-capable, near-instant repeat visits.