I have been playing on two rigs. One is my home machine i7 2600 with 16gb's of ram and 2x gtx570's and I get decent FPS at around 50-60 (with vsync) with only minor drops at times. This is on a mostly high settings with sbao and 2xAA.
At work I have a core i7 3770, 8gb ram and a single gtx570 and I get between 40-50 on all medium settings with sbao and 2xAA.
I know that the Beta drivers that were released are rubbish for me. I had horrible frame rate drops until I rolled back to the WHQL drivers. Then there was the PB fiasco.....
All in all I like BF4. I am really waiting to see the other maps that come with the full game.