Desktop freezes and works very slowl after connecting external monitor

[Rafał]

The problem may be similar to https://bugs.launchpad.net/ubuntu/+source/xorg/+bug/1459551

ProblemType: Bug
DistroRelease: Ubuntu 15.04
Package: gnome-shell 3.14.4-0ubuntu1
ProcVersionSignature: Ubuntu 3.19.0-18.18-generic 3.19.6
Uname: Linux 3.19.0-18-generic i686
ApportVersion: 2.17.2-0ubuntu1.1
Architecture: i386
CurrentDesktop: GNOME
Date: Thu May 28 10:15:46 2015
DisplayManager: lightdm
InstallationDate: Installed on 2014-01-28 (484 days ago)
InstallationMedia: Ubuntu 13.10 "Saucy Salamander" - Release i386 (20131016.1)
SourcePackage: gnome-shell
UpgradeStatus: Upgraded to vivid on 2015-04-18 (39 days ago)

[Daniel van Vugt (vanvugt)]

Thank you for reporting this bug to Ubuntu.
Ubuntu 15.04 (vivid) reached end-of-life on February 4, 2016.

See this document for currently supported Ubuntu releases:
https://wiki.ubuntu.com/Releases

We appreciate that this bug may be old and you might not be interested in discussing it any more. But if you are then please upgrade to the latest Ubuntu version and re-test.

[Launchpad Janitor (janitor)]

[Expired for gnome-shell (Ubuntu) because there has been no activity for 60 days.]