Surviving your peak season without going down

An online retailer slows to a crawl during its festive sale — the few days that carry a disproportionate share of annual revenue. The response so far has been to over-provision all year as insurance, which is expensive and still doesn't guarantee the peak holds, because nobody knows where the system actually breaks.

The system: load testing that reproduces real traffic patterns rather than a synthetic average, to find the genuine limit. In practice the ceiling is rarely raw server capacity — it's usually database connections, a slow query under concurrency, or a third-party API rate limit nobody had tested against. Those get fixed specifically. Caching goes where it earns its place. Scaling rules are set and then verified under load, with a rollback path that's been exercised rather than assumed.

What changes: a peak the system holds through, and infrastructure sized honestly for the rest of the year.