After upgraded my Archlinux system to GNOME 3.12 and other updates, the Activities overview effect was sluggish. I just downgraded xorg-server package from 0.15.1 to 0.15.0 and now the performance is better. https://projects.archlinux.org/svntogit/packages.git/log/trunk?h=packages/xorg-server [ 11.584] (--) intel(0): Integrated Graphics Chipset: Intel(R) HD Graphics 3000 % pacman -Q | egrep '^mesa|intel|clutter|server' clutter 1.18.0-1 clutter-gst 2.0.10-2 clutter-gtk 1.5.2-1 intel-dri 10.1.0-5 intel-tbb 4.2_20140122-1 lib32-intel-dri 10.1.0-4 libva-intel-driver 1.3.0-1 mesa 10.1.0-5 mesa-libgl 10.1.0-5 xf86-video-intel 2.99.911-2 xorg-server 1.15.0-5 xorg-server-common 1.15.1-1 xorg-server-utils 7.6-3 Don't hesitate to ask more information...
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