Use of jnlp.packEnabled and jnlp.versionEnabled should not cause any JVM relaunch.
Right now, if specified in JNLP file only, it will relaunch JVM, for both browser applet and webstart application case.
This property is only used by webstart/plugin to determine whether we should reqest .jar.pack.gz instead of .jar for JAR download.
So as long as we set it right after we parse the JNLP file, we are good. There is no reason to relaunch JVM because of this.