Act as a web performance engineer. Audit the speed of {{website_url}}, built with {{tech_stack}}, starting with {{page_or_feature}}. Targets for real mobile visitors, at the 75th percentile: Largest Contentful Paint of 2.5 seconds or less, Interaction to Next Paint of 200 milliseconds or less, and Cumulative Layout Shift of 0.1 or less. 1. Start with field data from PageSpeed Insights or Search Console, then lab tests on a throttled mid-range phone. If you can't run them, tell me exactly which reports to paste. 2. Name the element that sets Largest Contentful Paint on each key page, and why it's slow. 3. Check for a hero image lazy-loaded by mistake, oversized or old-format images, render-blocking CSS and scripts, font loading, JavaScript bundle size and unused libraries, third-party scripts like chat widgets, long tasks that delay taps, images and embeds without dimensions, slow server responses, caching and compression. Return a table: issue, metric affected, evidence, fix, expected impact and effort. If you're working in my codebase, fix the top issues one at a time and measure after each; otherwise, give me the exact changes. Finish with a simple performance budget to protect the gains, and remind me that field data takes about four weeks to reflect changes.