Latency
// Definition
The time between sending a request and receiving the first byte of response. Lower is better. Often reported at percentiles (p50, p95, p99) since averages hide tail behaviour.
// Related terms
Response Time
Total time from request initiation to response completion. Includes latency plus transfer and processing time. The end-user-perceived performance metric.
Throughput
The amount of work completed per unit of time — requests per second, transactions per second. Higher is better.
Load Testing
Verifying system behaviour under expected production load. Confirms the application meets performance targets at typical concurrent-user counts before release.
Learn more · Non-Functional Testing Overview
Chapter 2 · Lesson 2: Key Performance Metrics — Response Time, Throughput, Latency