Performance issue

Hello all matrox users.

I am having a performance issue with mplayer using mga_vid in debian stable.  
Looking at all the advice online seems to indicate that -vo xmga will give 
the best performace.  However I have been seeing a slight jerky picture when 
the camera starts panning across a room or scenery.  I started adjusting lots 
of thinks to rectify this (hdparm upgrading kernel and debian to unstable, 
tweaking things) but what seems to work best is the following command.

mplayer -ao alsa -channels 2 -vo xv -dr -double -dvd-device /dev/cdrom dvd://1 

I guess the question is why this works better because direct rendering is (as 
far as i know) is more likely to work with xmga than xv, but in my case it 
works with xv and again as far as i can tell doesnt work with xmga.

Now i thought I best check with the experts to see if I am in fact using the 
best settings because I have a feeling that -vo xmga -dr should work and give 
me better performance.  Am I right or do am I using the best way with -vo xv 
-dr.

Any help appreciated

Dave

ps system Debian stable kernel 2.4.27 
mga_vid working
P111 700 512MB RAM
Matrox g400