xz doesn't have BCJ2 (though it does have an earlier BCJ filter), which allows for somewhat better compression of exes. BCJ2 produces separate streams which ind

xz doesn't have BCJ2 (though it does have an earlier BCJ filter), which allows for somewhat better compression of exes. BCJ2 produces separate streams which independently compress better. See for instance https://bugzilla.mozilla.org/show_bug.cgi?id=1514357 https://bugzilla.mozilla.org/show_bug.cgi?id=1514357, saves almost 10% on a Firefox installer (which uses 7-Zip) vs the complete update .mar file (which uses xz/liblzma).