Definition: Sprint hardening is an approach where testing such as performance testing is left until the end of a sprint or release, once all features are built, rather than done alongside development. It is sometimes called the big bang approach. Teams may also run a dedicated hardening sprint to stabilise the product before release.
So what? Leaving performance testing to the end delays time to market and makes changes more expensive, because problems are found when there's least time to fix them. Naming the pattern helps teams spot it and move testing earlier.
Examples: A team that only load tests in the final week before release, then has to delay launch to fix a bottleneck. A team replacing its hardening phase with performance checks in every sprint.
