Since building the OpenJDK is a heavy operation, the build system tries to make use as of much of the system resources as possible and reasonable.

However, on most machines except extremely high-end, this means that few resources are available for other processes. On a developer machine, building means that other work can get laggy and have poor response times.

There is a simple remedy for this! Using "nice" to lower the priority for the build process, so the build will wait for normal UI processes. A single "nice" when handling the parallel targets in Init.gmk is sufficient.