Thanks devils casper.
I tried the vesa driver as you suggested but the performance is even worse.
I finally downgraded the X server and went to using the ATIs fglrx driver following the instructions from these posts:
FedoraForum.org - Fedora 9 (F9) and ATI ( fglrx ) with working OpenGL! FedoraForum.org - Fedora 9 (F9) and Nvidia 173.08 with OpenGL!
Here is my script to do this based on these posts:
Script to downgrade the Xserver to Fedora 8 version.
#Remove the Xorg server and mesa libraries.
yum -y remove xorg-x11-server-Xorg xorg-x11-server-common
rpm -e --nodeps --allmatches mesa-libGL mesa-libGLU mesa-libGL-devel mesa-libGLU-devel glx-utils
#Download fedora8.repo and modify fedora.repo
cd /etc/yum.repos.d
wget
http://www.linux-ati-drivers.homecal...k/fedora8.repo
perl -i -pe "s/(\[.*\])/\1\nexclude=xorg* linuxwacom* rhpxl* mesa*/" fedora.repo
perl -i -pe "s/(\[.*\])/\1\nexclude=xorg* linuxwacom* rhpxl* mesa*/" fedora-updates.repo
#Install Development Tools/Libraries
yum -y groupinstall "Development Tools" "Development Libraries"
yum -y install kernel-devel
#Now, you are ready to install Xorg 1.3
yum -y groupinstall "X Window System"
yum -y install mesa-libGL mesa-libGLU mesa-libGL-devel mesa-libGLU-devel synaptics
# Optional, re-install compiz.
#yum -y install compiz-gnome compiz-fusion* gnome-compiz-manager ccsm
#Install the Livna driver
rpm -Uhv
http://rpm.livna.org/livna-release-9.rpm
yum --enablerepo=livna-testing install xorg-x11-drv-fglrx xorg-x11-drv-fglrx-libs akmod-fglrx kmod-fglrx
akmods --kernels `uname -r`
service fglrx restart
fglrx-config-display enable
This results in much better behaviour. I do get direct rendering capabilities and my glxgears FPS is up to about 1200-1300 on a freshly booted system for about 100 without direct rendering, so that is good.
However this does not eliminate the issue. The system performance does degrade over time even with nothing running. The problem definitely seems to be in X because just logging out and logging back in (which restarts the X server) gets rid of the problem. You do not have to reboot the system.
Don't know where to go from here though.
Thanks for your help - it set me down the path to using ATI's driver.