R9000 Pro slooow with accelleration enabled in dual monitor config

Radeon R9000 Pro (Sapphire) in Dual Monitor setup. Screen writes have
become intolerably slow. The system was fine before I used the Smart Gart
ap.

I loaded the monitor.inf files for my dual monitors all seemed to be okay.
But then I used the ATI SmartGart ap and all hell broke loose. Screen draws
were painfully slow and when I checked the same Gart settings were in use.

I've had to disable acceleration to get the 2D performance back where it
should be but I am afraid the 3D will suffer this way.

David

ASUS A7N8x Deluxe
512 Meg