Performance Optimization quiz

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

Which image format generally yields the smallest size at equivalent quality?

1. Which image format generally yields the smallest size at equivalent quality?
2. Which `Cache-Control` value is best for hashed static assets?
3. A blocking CSS file is 80 KB and includes both above-the-fold and below-the-fold styles. Best fix?
4. What is "tree shaking"?
5. Why declare `width` and `height` on images?
6. What does enabling Brotli compression on the server give you?
7. A hero image is loading slowly and hurting LCP. Which attribute helps most?
8. Why is "shipping less JavaScript" usually the highest-leverage perf improvement?
9. What does the Lighthouse "performance" score primarily measure?
10. What does `loading="lazy"` on an `<img>` do?
11. When should `<link rel="preload">` be used?
12. What does `<img srcset="img-1x.jpg 1x, img-2x.jpg 2x">` accomplish?

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