Performance testing, or load testing as it is sometimes called, evaluates a system's behavior under high loads. Load testing is the process of determining how an application behaves when subjected to different loads ranging from low to high-level stress tests. The main goal of performance testing is to find and fix issues before they happen in production, preventing performance issues in production and possible downtime.
For C# applications, there are various performance testing libraries that can ensure the application’s quality under heavy load, validating its overall stability. This list gives best out of them xunit-performance - Provides extensions over xUnit to author performance tests; WebApiBenchmark - Web api management and performance testing tools; SqlProxyAndReplay - performance testing services that depend upon a SQL database.