GNU IceCat has been released a new version, based on Firefox ESR on the same version.

Main features:

1.- Inclusion of FLAC códec.
2.- Multiprocess windows (a.k.a. "Electrolysis"). The bundled version of GNU LibreJS add-on has been disabled due to the incompatiblity with this feature.
3.- Along with many performance and security improvements.

More improvements here: http://git.savannah.gnu.org/cgit/gnuzilla.git/tree/data/Changelog.IceCat
More information: http://lists.gnu.org/archive/html/bug-gnuzilla/2017-04/msg00008.html

Please note that this announcement has not been shared into the GNU Savannah project page. Otherwise, you can go to get more info about the development going to the GNU Savannah project page (http://savannah.gnu.org/projects/gnuzilla) or also in the official webpage (https://www.gnu.org/software/gnuzilla/).

Thanks.