How a CTO Used Load Testing to Prevent a Black Friday Meltdown

Tech Leadership with Fexingo: Engineering Managers, CTOs, and Technical Leadership Conversations · Jun 21, 2026 · 8m · transcript

In this episode, we unpack the story of a CTO at a mid-size e-commerce company who ran a series of load tests six weeks before Black Friday and discovered that a single database query would have taken down the entire checkout system under expected traffic. Lucas walks through the engineering choices — why they used k6 for scripting, how they simulated realistic user journeys, and the specific bottleneck they found in a PostgreSQL query that had been fine in staging. Luna pushes back on whether load testing is overrated compared to chaos engineering, and Lucas explains why the two serve…