AMD has released the ATI Catalyst 12.3 driver for Linux. It has a great improvement on performing with Ubuntu 12.04 Precise.

Here’s the ATI Catalyst 12.3 installation guide. Do it at your own risk!

1.) Open the terminal and execute following commands to remove current amd driver:

sudo sh /usr/share/ati/fglrx-uninstall.sh
sudo apt-get remove --purge fglrx fglrx_* fglrx-amdcccle* fglrx-dev*

2.) Install required packages:

sudo apt-get install build-essential cdbs fakeroot dh-make debhelper debconf libstdc++6 dkms libqtgui4 wget execstack libelfg0 dh-modaliases linux-headers-generic

For 64-bit, install this:

sudo apt-get install ia32-libs dkms

3.) Now, download ATI Catalyst 12.3 and give its execute permission.

cd ~/
mkdir catalyst12.3
cd catalyst12.3/
wget http://www2.ati.com/drivers/linux/amd-driver-installer-12-3-x86.x86_64.run
chmod +x amd-driver-installer-12-3-x86.x86_64.run

4.) build and install the deb.

sudo sh ./amd-driver-installer-12-3-x86.x86_64.run --buildpkg Ubuntu/precise
sudo dpkg -i fglrx*.deb

5.) After the setup wizard:

create the configuration file by:

sudo aticonfig --initial -f
sudo aticonfig --input=/etc/X11/xorg.conf --tls=1

Now, reboot!