Website Performance Optimization & Reporting Flashcards

Which technique reduces render-blocking and improves page load for non-critical JavaScript?

Answer: Using async or defer attributes

Async and defer prevent scripts from blocking HTML parsing.

How does a CDN generally improve website performance?

Answer: By serving content from locations closer to users

Edge servers reduce latency by delivering cached assets from nearby locations.

Which analytics observation most strongly suggests a page-speed problem hurting engagement?

Answer: High bounce rate with slow load times on mobile

Slow load correlated with high mobile bounce suggests users leave before the page renders.

What is the primary benefit of setting explicit width and height on images?

Answer: Preventing layout shifts

Reserved dimensions stop content from jumping as images load, improving CLS.

In reporting, why is a performance budget useful?

Answer: It sets limits on metrics like page weight or LCP to prevent regressions

Budgets define acceptable thresholds so teams catch performance regressions early.

Which tool provides both lab diagnostics and real-user field data for a URL?

Answer: PageSpeed Insights

PageSpeed Insights shows Lighthouse lab results alongside CrUX field data.

When attributing a revenue increase to a site speed improvement, what should an analyst do?

Answer: Compare against a control or account for other changes like campaigns and seasonality

Isolating the effect requires controlling for confounders such as promotions and seasonality.