I have an i5 3.4ghz dual core CPU, a Geforce 650 GTX 1gb, and 4gb of ram, Windows Vista, and I am running on a solid state drive.
On multiplayer I am running the game on med/low at 720p with no AA and 4xAF and my performance is great until the explosions start going off. I will get 30+fps on Gulf of Oman when flying over the water, but ~15fps when I am in the city. Games like CS:GO or TF2 run lighting fast on all max with AA and AF. I expected better from BF3. I know it a resource hog, but I should be able to get a fast framerate at low settings. Is this a known thing? Does the game chug at times for everybody, or do I need an even beefier desktop?