Created attachment 36788 [details]
My xorg.conf

I have tried to use all last xorg-server versions, but always get same problem.
:(.
My environment:
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Linux  version: Gentoo
platform: x86 (Pentium 4)
xorg-server: 1.6.5, 1.7.6-r1, 1.8.1.902
kde: 4.4.5
драйвера nvidia: 190.42-r3, 190.42-r3
kernel: sys-kernel/zen-sources-2.6.33_p3, gentoo-sources-2.6.33-r2
all visual effects: disable;
composite mode: disable:
opengl direct rendering: yes
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After some time (1-2 hours), system begin slow working:
1. Cursor breaks text in graphics text editors (kmail, kate, etc.)
2. Scrolling begin uneven in browsers and Eclipse etc.
3. Slow switch between virtual screens in KDE-4.4
4. All system begin very very slow.
5. xorg-server utilizes 50-60% CPU.

This is happens at my working PC. At home, my DELL inspiron 9400 (Core2 Duo)
work OK (x86-64).

IMPORTANT: 
If I switch to other console (ex: Ctrl+Alt+2) and back in X, then performance
has repaired!. But after several time same problem happens again.

May be problem with fonts rendering?

Reproducible: Always

I have install kde-4.4.5. and updated all x11-* libraries.
Steps to Reproduce:
----
1. I have entered into KDE-4.4.5.
2. Open ~100Kb text file in any editor (Krusader editor & Kate for me).
 (Xorg utilize CPU ~ 2%)
3. Push arrow down button - > scrolling work without yankes.
4. Push arrow right button - > cursor move without yankes.
5. Work several time in system. (10-15 m.)
6. Open the same text file in any KDE editor.
7. Push arrow down button - > scrolling work with sensible yankes!!! (Xorg 
  utilize CPU increase up to 60%)
8. Push arrow right button - > cursor move without sensible yankes!!! (Xorg 
  utilize CPU increase up to 60%)
9. Switch to other console (Ex.: Ctrl+Alt+2) 
10.Switch back in X
11. Push arrow down button - > scrolling work without yankes.
12. Push arrow right button - > cursor move without yankes.
 (Xorg utilize CPU decrease down to 2%)
13. Work several time in system. (10-15 m.)
14. Open the same text file in any KDE editor.
15. Push arrow down button - > scrolling work with sensible yankes!!!
16. Push arrow right button - > cursor move without sensible yankes!!!
 (Xorg utilize CPU increase up to 60%)
17. ...

Actual Results:  
System slow work

Expected Results:  
System work very fast