Myth: Preload key resources to speed them up Added 9 : LCP 2.0s -> 2.7s. Preload tells the browser to fetch at highest priority immediately. Stack too many and they compete for bandwidth with the actu…
Myth: HTTP/2 killed bundling, ship many small files Unbundled 1 file into 60 modules: transfer same, TBT 180ms -> 340ms. HTTP/2 multiplexing removed the per-request connection penalty, so the old "con…
Myth: async and defer do the same thing Swapped defer for async on 3 scripts: FCP 1.2s -> 1.2s, but LCP 2.1s -> 3.0s. Both download without blocking the parser. The difference is execution timing. — a…
Diagnose hydration cost in an SPA framework Hydration (attaching JS interactivity to server HTML) runs as one big task that spikes TBT and delays INP readiness. — Step 1: Performance panel — find the …
Myth: Lazy-load all images for speed Lazy-loaded the hero: LCP 1.8s -> 3.6s. loading="lazy" on the LCP image defers its fetch until layout/scroll checks pass, adding a request round-trip before the br…
Myth: A CDN fixes slow TTFB Added CDN: TTFB 620ms -> 600ms. Expected sub-100ms. Why? TTFB (time to first byte) = network RTT + server think-time. A CDN cuts network distance, not your origin's databas…
