Crash Courses · Basic
Browser Performance and Web Vitals
LCP, FID, CLS, critical render path
12 min read+200 XP on completionCert: Frontend Engineering
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# Browser Performance
Core Web Vitals
LCP under 2.5s, FID under 100ms, CLS under 0.1.
Critical Render Path
HTML parses into DOM, CSS into CSSOM, both combine into Render Tree, then Layout calculates positions, Paint draws pixels.
Techniques
Lazy load images and components. Code-split with dynamic imports. Preconnect to third-party origins. Use a CDN for static assets.
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