perfmedium
A page loads slowly. How do you diagnose and improve it?
Answer
Measure before changing anything — a Lighthouse run and the network waterfall tell you whether the cost is bytes, requests, or blocking work. Common wins: serve modern image formats at the right size, lazy-load below-the-fold media, defer non-critical JavaScript, subset fonts and use font-display: swap, and cache static assets aggressively. Then re-measure against a real metric like LCP rather than a feeling.
Points an interviewer listens for
- Measure first: Lighthouse, network waterfall
- Images: right size, modern format, lazy below the fold
- Defer non-critical JS; trim and subset fonts
- Verify against LCP/CLS, not impressions
Reported at
Similar questions have been reported by candidates at Northcorp Software, Cognizant, Pocket FM, Tekion, Tekwissen, Accenture.
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