The IBM® JIT compiler is tuned for long-running applications typically used on a server. You can use the -Xquickstart command-line option to improve the performance of short-running applications, especially for applications in which processing is not concentrated into a small number of methods.
-Xquickstart causes the JIT compiler to use a lower optimization level by default and to compile fewer methods. Performing fewer compilations more quickly can improve application startup time. When the AOT compiler is active (both shared classes and AOT compilation enabled), -Xquickstart causes all methods selected for compilation to be AOT compiled, which improves the startup time of subsequent runs. -Xquickstart can degrade performance if it is used with long-running applications that contain hot methods. The implementation of -Xquickstart is subject to change in future releases.
You can also try improving startup times by adjusting the JIT threshold (using trial and error). See Selectively disabling the JIT compiler for more information.