Performance Optimization quiz

Test your Performance Optimization knowledge with a free interactive quiz — 50 questions with answers and explanations. No signup needed to play.

A blocking CSS file is 80 KB and includes both above-the-fold and below-the-fold styles. Best fix?

1. A blocking CSS file is 80 KB and includes both above-the-fold and below-the-fold styles. Best fix?
2. What does `<img srcset="img-1x.jpg 1x, img-2x.jpg 2x">` accomplish?
3. Which `<script>` attribute lets the browser continue parsing HTML while the script downloads, and runs the script only after the document is parsed?
4. A page has a 2 MB JavaScript bundle. Which is the most effective first fix?
5. What does enabling Brotli compression on the server give you?
6. What does the Lighthouse "performance" score primarily measure?
7. Which image format generally yields the smallest size at equivalent quality?
8. Which CSS animation property is GPU-accelerated and cheap to animate?
9. What does TTFB (Time to First Byte) measure?
10. What is "code splitting"?
11. A hero image is loading slowly and hurting LCP. Which attribute helps most?
12. When should `<link rel="preload">` be used?

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