Web Performance (Core Web Vitals, Lighthouse)

Web performance is the discipline of making websites fast across all network conditions and devices. The three Core Web Vitals (LCP, FID, CLS) measure loading speed, responsiveness, and visual stability—Google's 2021 ranking factors that directly correlate with user retention and conversion. LCP (Largest Contentful Paint) targets < 2.5s, INP (Interaction to Next Paint) targets < 200ms, CLS (Cumulative Layout Shift) targets < 0.1. Tools like Lighthouse, WebPageTest, and SpeedCurve quantify performance across real user monitoring (RUM) and synthetic testing. At scale, a 1-second latency reduction = 3-7% conversion lift and 20%+ bounce rate improvement; this translates to millions in revenue for high-traffic sites, making performance engineers sought-after at scale-ups and enterprises. Web performance is a $20-45k/year salary lever. Junior frontend developers ($80-120k) miss this skill; mid-level engineers with performance expertise command $130-160k; seniors ($180-250k+) often define performance architecture at high-traffic companies. Google's Core Web Vitals ranking algorithm (live since 2021) means every SaaS, e-commerce, and media company pays for performance—driving structural job growth. The gap narrows in 2026 as AI improves developer velocity; differentiation moves from "shipping features fast" to "shipping features that are fast." Performance engineering is one of the last pure competitive advantages—automated tests don't catch all UX issues, and hiring exceptional performance engineers is hard. Companies like Shopify, Vercel, and Netflix hire performance engineers at senior levels ($180k-$250k) because the ROI is measurable.