System Design · Senior · Question 31 of 75
Why is it important to look at p99 latency and not just the average?
- ✓Correct answer: The average hides the slow "tail" of requests
- 2p99 is always lower than the average and looks better in reports
- 3The average can't be computed for network requests
Explanation
If a page makes 20 requests, the probability of hitting at least one slow one is high, and the user waits for the slowest. That's why SLOs are stated in percentiles (p95, p99), and Web Vitals are assessed at the 75th percentile.