High X server CPU usage when drawing

["Rafael E. Herrera" <raffo@xxxxxxxxxxxxxxxxx>]

Hello,

I'm developing an application using the motif toolkit to display line 
traces in the manner of a multichannel osciloscope. This is a linux 
platform.

The window draws a number of horizontal traces obtained from a data 
source. When we started using the xinerama extension or very large 
resolutions (> 1280x1024). We started observing an undesirable behavior:

The application, when is resized, re-creates the pixmaps where the data 
is drawn. The old ones are freed and new ones are created according to 
the new size of the window. Then, the program continues operating by 
receiving new data periodically and drawing them.

The problem is that _sometimes_, after resizing to a new window size 
(usually larger than the old one and relatively large compared to the 
screen size) the application slows down and does not draw new data as 
fast and the X server hits more than 97% of CPU usage. The problem is 
serious because if the user clicks on the application to get the menu, 
the pointer gets grabbed but nothing happens for several minutes and the 
machine is effectively locked.