The Complete Guide to Web Performance
Page speed is the silent salesman. Every 100 ms of delay costs conversions, and the first screenful decides whether a visitor stays or bounces.
Core Web Vitals turn that intuition into three numbers you can track release over release — and argue about in standups.
Teams that set a performance budget ship 2.3× fewer regressions.
Start with the largest image above the fold, defer everything the user cannot see yet, and measure again. The rest is discipline, not magic.