Different performance with different user accounts?

[Ancoron Luciferis]

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Hi *,

I have experienced that for some time now but never got the time to ask
about it.

I have a machine with two user accounts under Kubuntu 9.10 and the
performance difference I am experiencing is measurable. The first user
account (set up during installation time) works good. Glxgears is around
4000 FPS, video playback is fine, compositing is fine (especially the
desktop cube is fast as hell and really smooth).

On the other hand there is a second user account (this one is not in the
admin group but basic setup is the same). In that user account I get
only around 2700 FPS, compositing works fine (the cube is still that
fast) but moving windows around is dead slow and video playback is NOT
"tear-free". The rather strange thing is that it doesn't depend on video
source frame size or codec or scaled frame size, the playback is just
dropping frames especially when there is a lot of movement.

Turning off the compositing results in a fast user experience but since
it is fast with compositing for the first user I expected it to be the
same for the second one.

CPU usage is not the problem as the quad-core machine is idling around
between 70% and 90% although Xorg is between 30 and 50% and mplayer
between 1% and 26% (peeks up to 47%) when watching a movie.

System:
- - AMD Athlon II X4 620
- - 4GB RAM
- - Radeon X1950XTX
- - Dell 3007WFP-HC 30" @ 2560x1600

This doesn't make sense for me at all.

Can someone shed some light on this?

Thanx a lot,

Ancoron
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