Slow performance with newer xorg-X11

When I connect to my win2003 terminal server I get annoyingly slow
performance in oultlook, symptom is that outlook redraws everyting
twice and that switching application takes a very long time.
This happens when I connect from Fedora10 but not from Fedora9.

I have tried mixing the rdesktop binaries and that is not the problem,
I have also tried all the flags for rdesktop and also tried disabling
font smoothing etc on the server side. Even if I from my f10 ssh to a
f9 machine with x11-forwarding and run the client threre the problem
appears. So I have good reason to think its some kind of compability
issue between the rdesktop client and the x11 server.

Have anyone else got closer to a sollution than me?

Versions:
F9 xorg 1.5.2: problem free.
F10 xorg 1.5.3: problem.
F11 xorg 1.6.0: problem.
F9 client with all libs to remote f10 server: problem.

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