Strange speed differences on composite

[Tomasz Torcz]

  Hi,

  recently I've noticed something suspicious going on with compisite
speed. 
  First subject was Xephyr, CVS version dated 11th August 2005,
build using jhbuild. I turned it on as a 1024x768 window with GNOME
session inside. The I've run "xcompmgr -c" inside. Shadows appeared.
Now, moving windows in this Xephyr window is pretty fast and CPU isn't
used much (10% max), so it's pretty usable.
  Second test was on normal X server. I'm running Xorg 6.9.0 from
Slackware -current, my graphics card is Matrox G550 with mga driver
and Semprom 3500+ CPU. EXA is not available on mga.
When I run "xcompmgr -c" everything becomes very slow. Window movement
is painful with cpu stuck at 100%. Switching to other virtual desktop
takes 2-3 seconds to redraw windows.

  The question: how it comes that software-only Xephyr is _faster_ at
drawing shadows than fully hw accelerated X server with mga driver?

-- 
Tomasz Torcz            There exists no separation between gods and men:
zdzichu at irc.-nie.spam-.pl   one blends softly casual into the other.

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