Practice reading load charts in a safe simulation before you spend a minute generating real traffic from your machine.
Find a tipping point in the load lab
The Load lab below is a simulation inside LiftOff — not Postman, and not real traffic to Sample APIs. That’s intentional.
Why practice here first? Real Performance runs take time, use your machine (or cloud VU hours), and are awkward to replay while you’re still learning what a healthy chart vs a breaking chart looks like. The lab lets you turn virtual users up and down until you can see a tipping point — avg staying relatively calm while p95 and errors climb. That pattern is exactly what you’ll look for in Postman’s live metrics next.
The lab is tuned so the simulated API stays healthy until roughly 80 concurrent users, then degrades.
- Set virtual users low (~20) and click Run test. Confirm avg and p95 look calm.
- Raise virtual users past 80 and run again.
- When the breakpoint badge appears, read the summary chips — notice how p95 and errors move relative to the average.
Expected outcome: You’ve found the knee near 80 VU and can describe what changed on the chart.
Load lab
Practice reading load charts here first — simulated Fixed load, no traffic leaves this browser. Then you'll look for the same patterns in Postman.
Tip: start low, then push past ~80 VU. Watch p95 and errors, not only the average.