Case Study: Performance Testing in the Payment Industry

We recently completed an engagement for a payment processing company in London. The project was delivered on time and on budget, uncovering critical architectural bottlenecks before they impacted production merchants.

What We Did

1. Defined Actionable Requirements: Gathered concrete performance requirements with stakeholders even though no formal SLAs were previously documented.
2. Architected the Test Framework: Designed a modular framework covering load, capacity, stress, and spike testing.
3. Custom Locust.io Implementation: Built the execution engine on Locust.io with heavy customisation for payment signing, asynchronous webhooks, and realistic merchant traffic shapes.
4. End-to-End Python Analytics Pipeline: Built a proprietary performance test data processing framework in Python (NumPy + Pandas) to correlate client-side latencies with backend queue depths.
5. Pinpointed the Real Bottlenecks: Within a few weeks of executing load, stress, capacity, and spike tests, we identified the true system bottlenecks—which turned out to be completely different from what the internal teams suspected.
6. Verified the Fix: Proposed and helped implement targeted changes that delivered a step-change improvement in transaction throughput and tail latency.

Working on a high-throughput payment or financial platform? Let's talk through your capacity goals.