OOo’s helpcontent2 is notoriously slow to build. gcj users can try out the testing issue 54692 patch to improve buildtime. Comparisons here are for just the “sbasic” HelpLinking in helpcontent2/util/sbasic.
1:02:31 generic gij invocation against aot compiled jars
0:18:55 custom gcjed to native code HelpLinker