搜索了一下網上的解決方法:
1,
sudo gedit .xprofile
export UNITY_LOW_GFX_MODE=1
發現還是不行。
2,然後看到下面這個,試了一下,解決了。
Same problem with a Dell PowerEdge R720, video card Matrox Electronics Systems Ltd. G200eR2
I try many ways but no one can be work fine with the ubuntu 14.04 ,
when i google the G200eR2’s driver, i found a solution with this card, remove the mga driver!
sudo apt-get remove xserver-xorg-video-mga
it will remove the xserver-xorg-video-mga and xserver-xorg-video-all
then reboot
now the window not slowly, and screen only has a 800x600 @75hz , but it work fine
i hope this way can help other people
或者也可以看原網頁
https://bugs.launchpad.net/ubuntu/+source/xorg-server/+bug/1316035