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Guides

Guides from the Evaluat team: articles on real-browser performance testing and Core Web Vitals.

Load testing: concurrent virtual users ramp up, hold at a steady load, then ramp down, with each virtual user running in its own browser.

What is performance testing? A QA engineer's guide to testing under real traffic

Your app works fine for one user. Then a launch sends three thousand at once and pages crawl. Performance testing is how QA teams measure speed, stability, and scale under real traffic, on purpose, in a test instead of in production. This guide covers what performance testing is, its types, and when to run it.

Ahmad Farzan ·

The cost of one virtual user. A protocol virtual user in a load tool like k6 costs about 1 to 5 megabytes, so one machine runs tens of thousands of them, shown as a dense field of dots. A real-browser virtual user driven by Playwright costs hundreds of megabytes and about one CPU core, so one machine runs only dozens to low hundreds, shown as a few browser windows. Roughly 50 to 100 times more compute per user.

Playwright for performance testing: can a browser automation tool drive virtual users?

You already know Playwright for end-to-end tests. Can you reuse it for performance testing and call each browser a virtual user? You can, but a real browser is expensive to run, so it drives a handful, not a flood. Here is how far Playwright scales, and where you reach for a different tool.

Ahmad Farzan ·

A release cycle drawn as five stages from planning to production. The weight of each performance test grows from light checks on every commit to a heavy real-browser load test at the pre-release gate, then tapers to monitoring in production.

Where does performance testing fit in an agile release cycle?

Agile teams ship every week, sometimes every day. Performance testing built for a quarterly release does not fit that rhythm, so it slides to the end, then to never, until production buckles. It does not have to. This guide maps each performance test to a stage: cheap checks every commit, a real-browser load test at the pre-release gate, monitoring after.

Ahmad Farzan ·

A performance test timeline. The server answers in 0.28 seconds, but the page is not usable until 4.3 seconds under load, well past Google's 2.5-second LCP budget. The gap is everything the browser does after the server responds: rendering, JavaScript, and third-party tags.

Performance testing: the complete guide

Your server can answer in 50 milliseconds and still ship an eight-second page. Performance testing is how you measure what users actually experience under load, not just what the backend returns. This guide maps the whole discipline: the types, the metrics that matter, the process, and how to choose between protocol-level and real-browser tools.

Ahmad Farzan ·