I am running a triple head setup with two 7900GS cards, 3D performance is lovely.
However, 2d is impossibly slow. Anti-aliased fonts take a long time to render, for example reading a 700kb java class in kate, I can hold PageDown for ~3 seconds and Xorg takes ~1 minute before it is finished with the CPU. Dragging windows leaves a long trail, etc etc.
This only happens in Xinerama. If I set up two monitors in twinview, there is no such problem and everything is fast - but I need three so that is no good.
I also get the 2D slowness problem if I have two monitors connected to the same card in Xinerama. If they are on different cards it is faster, but still slow.
Enabling or disabling composite or RenderAccel seem to have no effect.
Attached is an autogenerated nvidia bug report file for the setup with all three screens.
"Your file of 149.6 KB bytes exceeds the forum's limit of 146.9 KB for this filetype"
I think this has been touched on before, but only in a dualhead context, so the answer has always been "use twinview", but that doesn't help me..
So.. Any ideas? :/