关闭Ubuntu下的3D效果

在虚拟机上装了个Ubuntu之后，发现运行很卡，通过ps命令查看后发现，有个compiz进程占用了很大的cpu和内存资源，经过查阅资料得知，Ubuntu下的3D效果需要用到这个进程。

为了提升Ubuntu的运行性能，我们最好关闭3D效果，具体方法如下：

Install gnome-session-flashback and consider disabling the visual effects

By default, when your video card can handle it, the 3D visual effects are enabled. However, these may cause malfunctions or sluggish performance. Consider disabling them, which you can do by switching to a 2D desktop environment.

Note: this applies only to Ubuntu and not to Xubuntu or Lubuntu.

There are several options for this.
My personal favourite is a switch to the Xubuntu desktop. But there's another option as well:

a. First, install gnome-session-flashback:

Click on the grey Ubuntu logo (Dash home). Query: terminal. 
Click on Terminal.

Type (use copy/paste):
sudo apt-get install gnome-session-flashback

Press Enter. When prompted, type your password. Your password will remain entirely invisible, not even dots will show, this is normal. 
Press Enter again.

b. Log out. In the login window, click on the Ubuntu logo next to your user name (see the screenshot below):

Then click on GNOME Flashback (Metacity).
Note: don't select GNOME Flashback (Compiz), because that also has 3D effects, and you want to get rid of those.

c. Log in again.

摘自：https://sites.google.com/site/easylinuxtipsproject/first