Experimental project trying to reproduce a bug in jgit.
The problem observed was described in https://www.eclipse.org/lists/jgit-dev/msg03770.html
Basically after jgit gc with default options, all push operations may becomes slower due to inefficient counting of the objects to send. In some repositories the effect was huge (from 4s to 2 minutes), in some repositories there was no effect.
A workaround is to set pack.singlePack=true in the git config, which can programatically be done like this:
git.getRepository().getConfig();
config.setBoolean("pack", null, "singlePack", true);
config.save();