I have upgraded from Ubuntu Gnome 14.04 to 14.10 yesterday using standard Software Updater GUI. The upgrade went smooth, however once upgrade was done I've noticed significant desktop performance degradation only when certain applications are running at the time. Basic desktop operations like switching between workspaces is accompanied by visible lag and stuttering, which is extremely annoying and disruptive in daily workflow.
I've recorded a screencast demonstrating this problem - I've used standard Image Viewer application (ver. 3.12.2) and Google Chrome as example apps causing this issue - which is not to say that these are ONLY applications causing it.
The screencast video: https://www.youtube.com/watch?v=0LhKhdgKHiQ
I've googled around this issue and tried several workarounds related to GPU's hw acceleration, yet none of these attempts fixed the problem.
Any help or pointers would be much appreciated.
As suggested in the comment below, I've executed glxinfo to gather additional graphics/acceleration data, however I don't have a clue how to read this: http://pastebin.com/JRuTgQSa
Additionally, I've filed a bug report in Launchpad: https://bugs.launchpad.net/ubuntu-gnome/+bug/1385764