I've been getting the same problem with performance using a Radeon 9800 (in my case, it's XT). As of this post, the ATI drivers provided that can be used on Fedora Core 4 are :
ATI Driver Installer (.run file) Version: 8.22.5
X.Org 6.8 (.rpm file) also Version: 8.22.5
At some point I overlooked the fact that the new installer doesn't include fglrxconfig and wasted some time trying to find it/getting it to run. Now, as stated in the instructions, you have to use ATICONFIG to set up your card. However, even after reading the documentation, making sure that the default ATI drivers have been removed prior to installation and then running the installer, everything as root, I still get this when I use the fglrxinfo command:
OpenGL vendor string: Mesa project: www.mesa3d.org
OpenGL renderer string: Mesa GLX Indirect
OpenGL version string: 1.2 (1.5 Mesa 6.2.1)
Worse is the fact that when I use the ATI Control Panel, in the OpenGL section, I get 8.21.07 as the driver version. Isn't it supposed to be 8.22.50? What exactly does one have to do to get proper opengl configuration running? I know that this is the result I'm supposed to obtain (this is just an example taken from another page where a 9700 was configured properly):
OpenGL vendor string: ATI Technologies Inc.
OpenGL renderer string: RADEON 9700 PRO Generic
OpenGL version string: 1.3.5395 (X4.3.0-8.18.8)