On Optimizing React Performance

The exact steps a browser takes from URL → rendered page
What triggers style recalculations, layout shifts, and paints
How JavaScript execution blocks rendering
How network waterfalls impact LCP & TTFB
Why microtasks and macrotasks change UI responsiveness
How caching layers (memory → disk → CDN) shape performance
Why a small CSS change can cause massive layout thrashing Master the browser. Everything else compounds from there.