This document discusses performance testing of Java applications and the tools used at AdoptOpenJDK. It provides an overview of the scope of testing done at AdoptOpenJDK across multiple Java implementations, platforms, and versions. It defines key performance metrics and the basic steps of performance testing. Tools used at AdoptOpenJDK are introduced, including PerfNext for running benchmarks, the Test Results Summary Service for analyzing and comparing results, and BumbleBench for simplifying microbenchmark implementation. The document encourages open collaboration to advance innovation in performance testing.