Ubuntu’s GUI response is very slow

For Dell PowerEdge T630 server, if you install latest Ubuntu desktop version (16.04) or (14.04), you will get a very slow GUI (X-window).

$ inxi -G
Graphics:  Card: Matrox Systems G200eR2 X.org: 1.15.1 driver: vesa tty size: 205x58 Advanced Data: N/A out of X

For Ubuntu 14.04.1, this problem can be solved by following steps.

1, Switch to console mode

CTRL + ALT + F1

2, Stop lightdm service

sudo service lightdm stop

3, Generate Xorg new configure file:

sudo X -configure

4, Move the Xorg configure file to system dir:

sudo mv xorg.conf.new /etc/X11/xorg.conf

5, Open ‘/etc/X11/xorg.conf’ and substitute ‘mga’ to be ‘vesa’

6, Start lightdm again with new configure file

sudo start lightdm

For Ubuntu 16.04, this problem seems to be there and cannot solve by above way.