Performance work starts with real user measurements and targets the slowest part of the experience.
Measure loading and interaction on representative devices and networks. Field data reveals delays that a fast developer machine can hide.
Prioritize likely causes: oversized images, render-blocking resources, unnecessary JavaScript, and slow server responses. Set media dimensions and defer below-the-fold assets.
Recheck the same measurements after each change. Track regressions in release workflows so performance remains part of product quality.
