Graphics speed depends on user profile

Juan Pablo de la Cruz cruz at
Thu Nov 20 08:58:22 PST 2014

Hello everyone,

We have an library which directly uses the Xlib API to do graphics.

We are observing the following effect: when two different users log
in the same machine, use the same window manager, and run the very same
program, the graphics are slower (much) for one of the users.

Concretely, the user for which the drawing is slower, logs himself in,
and the other user executes su $USER on the terminal.

Both use the exact same libraries (same PATH and LD_LIBRARY_PATH).
Both use the same window manager.

What other settings/factors could explain this behaviour?
Could you point me to some source/guide providing some helpful information?

Currently I am out of ideas.

Thanks and greetings,
Juan Pablo

Juan Pablo de la Cruz Gutierrez               cruz at
MVTec Software GmbH | Neherstr. 1 | 81675 München  | Germany | Tel: +49 89 457695-0 | Fax: +49 89 457695-55
Geschäftsführer: Dr. Wolfgang Eckstein, Dr. Olaf Munkelt
Amtsgericht München HRB 114695

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