ClickHouse is a fast database management system that relies on architectural choices and algorithmic optimizations to achieve its speed, with performance measurements taken through various benchmarks and tests. The system uses an automated test process that compares the performance of different versions of the code, using metrics such as elapsed time, maximum query run time, and median query run time. The performance test system also tracks changes in query metrics over time, providing a history of performance changes for queries. To ensure usability, the system aims to minimize false positives and provide concise reports that make it obvious what went wrong. However, implementing this system comes with challenges, such as preventing developers from devolving into "mining the green check" behavior and ensuring that the test process is not too complex or time-consuming.