Xorg with composite enabled causes abnormally high cpu usage

[eXtace]

Ubuntu 7.04 using kubunut desktop, NO DESKTOP EFFECTS enable whatsoever, nvidia driver. (tried with stock ubuntu repo one, and latest 100.14 version via envy with same exact results.

If the COMPOSITE extension is enabled in the /etc/X11/xorg.conf gtk-1.2 apps that are graphics intensive (I use my app, eXtace (in the repos) as it does extensive 2D calls) causes Xorg to use about 40x more CPU and perform sluggishly compared to when composite is disabled in the /etc/xorg.conf.

thus. If composite is disabled as below:
Section "Extensions"
    Option "Composite" "Disable"
EndSection

apps like eXtace will run liquid smooth, with minimal cpu usage (i.e. under 1-2% at 85 FPS on a 2.1 Ghz athlon.

If I enable composite via:
Section "Extensions"
    Option "Composite" "Enable"
EndSection

The the same exact app, eXtace will only run at 35fps consuming a steady 40% of the Xorg process only (NOT the eXtace process) Trying to increase frame rate severely harms gui responsiveness, and will max out CPU to 100% before even max framerate is achieved.

It seems that the composite extension is causing a rather serious performance bottleneck, though at this time is seems to be limited soemwhat to GTK-1.2 based apps that are 2D intensive. I'm unsure if the composite extension is causing any performance degradation to other 2D applications without further testing.

[Bryce Harrington (bryce)]

This package has become obsolete so we're closing out the bug report as WONTFIX.
Thanks for reporting it though!