I am using Ubuntu 11.10. I have a ATI RADEON HD6850 card (made by ASUS) and 3 monitors (DELL U3011 (30") and 2x DELL U2410 (24 ")).
I recently upgraded to Intel Sandy Bridge E 3930K processor and ASUS P9x79 pro motherboard. Proprietary driver causes system hangups with the new CPU/motherboard but worked fine on my older CPU (intel 750). The opensource driver works fine with single monitor (30 inch) with the new CPU.
Whenever I enable the second monitor, everything slows to a crawl -- typing in terminal shows a large lag. I used to use the two 24" monitors in potrait mode (rotated) with proprietary driver before. With the open source driver the rotation slows things even more. Is there any fix for it. Are there any tweaks to make the open source driver work better with multiple monitors with some of them rotated.