Currently, the following JVM options are systematically applied to JVMs running ITW applications:

# JVM options, emulated client, see https://developers.redhat.com/blog/2017/04/04/openjdk-and-containers/
-XX:+TieredCompilation
-XX:TieredStopAtLevel=1
-XX:+UseSerialGC
-XX:MinHeapFreeRatio=20
-XX:MaxHeapFreeRatio=40

As per the comments above them, these options aim to emulate the behaviour of the "client vm" as present in previous version of the JVM.
In particular, they would have the benefit of limiting the amount of non-heap memory used by the JVM, for TieredStopAtLevel=1 and +UseSerialGCs, and to make it more eager to release unused memory to the OS in the case of MinHeapFreeRatio and MaxHeapFreeRatio.

This however come at a significant cost in performance: in a customer use case consisting of the starting of a large (300+ jars) application based on NetBeans Rich Client Platform framework, we measured the startup time for the application (mostly spent on loading and initializing its many modules) went from 5 minutes with the above options, down to 3min 30s with the options removed (i.e. using JVM defaults).

We should really consider removing these specific options so that applications started using ITW would fall back to using the JVM defaults, which are arguably better suited to the task of running client application on modern hardware.