fc5 X performance is a mess!

[Boris Glawe]

My gpu is an nvidia geforce 5200, my machine is Athlon XP2800+ with 1GB 
PC3200 RAM on an Asus Board - short: my machine is very fast. I haven't 
installed any proprietary drivers from nvidia yet, since the kernel 
still refuses to load non-gpl modules and because nvidia's installer 
doesn't work properly with FC5.

Normal work on the desktop with both gnome and kde results in almost 
100% CPU usage all the time. The last time when I had such a slow GUI 
was, when I ran FC4 on a 300Mhz Pentium II. Browsing simple pages with 
maximized windows (for example: 
http://www.canon.de/For_Home/Product_Finder/Cameras/Digital_SLR/index.asp?ComponentID=164045&SourcePageID=26009#2 
) even locks up my whole desktop for seconds.

Top shows me that it's the X Server that eats up all my CPU.
The CPU usage is even that high, that the bandwidth of my dialup 
connection shrinks to a tenth of the normal rate while the X-server is 
calculating.

It's not only browsing the web. The whole desktop is much slower then 
before. Another example is the gnome-terminal. Actually it's not the 
gnome-terminal that eat's the cpu but the X-Server again. Anyway, when 
compiling things an a remote machine (via ssh) the X-Server consumes my 
whole CPU only because gnome-terminal requests to paint one line every 
tenth second. The remote machine compiles faster then my machine can 
paint the output!! A workaround is placing another window over the 
gnome-terminal. The CPU usage goes down to almost zero in this case.

Another strange thing is that I cannot always reproduce this behaviour. 
Sometimes things go fast sometimes my machine seems to have locked up 
for seconds.

Can you confirm this? In my case it's that bad, that I am going to delay 
an upgrade from FC3 to FC5 of about 50 Client machines. The GUI is in 
fact not usable!

What could be the reason for this? Is it the new cairo library in gnome?

thanks for hint!

greets Boris

P.s. There's one thing concerning performance, that I appreciate very 
much: it's the startup time for gnome. It's almost as fast as xfce!!