rsync: --xattrs is extremely slow

Ubuntu 16.04 LTS repositories contain only rsync version 3.1.1:

$ apt policy rsync
rsync:
  Installed: 3.1.1-3ubuntu1.2
  Candidate: 3.1.1-3ubuntu1.2
  Version table:
 *** 3.1.1-3ubuntu1.2 500
        500 http://fi.archive.ubuntu.com/ubuntu xenial-updates/main amd64 Packages
        500 http://security.ubuntu.com/ubuntu xenial-security/main amd64 Packages
        100 /var/lib/dpkg/status
     3.1.1-3ubuntu1 500
        500 http://fi.archive.ubuntu.com/ubuntu xenial/main amd64 Packages

However, this version has a bug where flag --xattrs causes very very high CPU usage if source contains lots of unique extended attributes. I'm trying to sync 13 TB (roughly 6.5 M files) with extended attributes and this bug seems to make this slower and slower as the time goes by. The system has been copying the stuff for three weeks (!) now. It's getting slower every day but still seems to make progress so I try to run it to completion. First couple of terabytes suggested that this sync operation should have taken around 4 days. The source directory is used by glusterfs which creates checksums as extended attributes and practically every file has different checksum.

Please, update rsync package on Ubuntu 16.04 to 3.1.2-2 or later.

See also: https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=799143

ProblemType: Bug
DistroRelease: Ubuntu 16.04
Package: rsync 3.1.1-3ubuntu1.2
ProcVersionSignature: Ubuntu 4.15.0-51.55~16.04.1-lowlatency 4.15.18
Uname: Linux 4.15.0-51-lowlatency x86_64
NonfreeKernelModules: nvidia_uvm nvidia_drm nvidia_modeset nvidia
ApportVersion: 2.20.1-0ubuntu2.18
Architecture: amd64
CurrentDesktop: MATE
Date: Tue Jul 2 09:07:49 2019
InstallationDate: Installed on 2015-02-23 (1589 days ago)
InstallationMedia: Ubuntu 14.04.2 LTS "Trusty Tahr" - Release amd64 (20150218.1)
SourcePackage: rsync
UpgradeStatus: Upgraded to xenial on 2016-06-10 (1116 days ago)