Performance is a conversion feature, not a technical detail
SalesGrowth · 2026-04-08 · 6 min read
How LCP, INP and CLS map onto real user behaviour, and the handful of changes that usually deliver most of the improvement.
Three metrics, three human experiences
LCP is 'did something useful appear'. INP is 'did the page respond when I touched it'. CLS is 'did the page move while I was reading'. Each maps to a distinct frustration.
Where the wins usually are
Oversized hero images, unoptimised formats and missing dimensions cause most LCP and CLS problems. Fonts loaded without a sensible fallback cause visible text delay.
Third-party scripts are frequently the largest single cost and the least examined. Audit what each one actually earns you.
Animate transform and opacity only. Animating layout properties is the most common self-inflicted performance wound.
Field data over lab scores
A perfect lab score on a fast laptop means little if your audience is on mid-range Android devices over patchy mobile networks. Test on the hardware your visitors actually use.