Image Performance Testing: Tools and Metrics to Measure Impact
Use Lighthouse, WebPageTest, and Chrome DevTools to measure image performance. Identify oversized images and missed optimization wins.
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Tags: image, performance, testing
Image Performance Testing: Lighthouse, WebPageTest, and CrUX Improving image performance starts with measurement. The tools available in 2025 give you three distinct perspectives: synthetic testing in a controlled environment (Lighthouse), deep waterfall analysis with visual filmstrips (WebPageTest), and real-user experience data aggregated from Chrome users in the field (CrUX). Using all three gives you a complete picture of how your images affect users in practice, not just in a lab. Lighthouse: The Starting Point Lighthouse is Google's automated audit tool, built into Chrome DevTools. It runs a synthetic test from your machine (or from a simulated mobile device) and reports performance scores, Core Web Vitals, and specific image optimization opportunities. Running Lighthouse Open…
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