Then I would come home, and fire up my home pc which is a lot more powerful (core i5 3.3ghz, 16gb ram, and a geforce 8800gt 512mb card and the results were dramatically different. Solid 60fps on high settings and much better responsiveness and control.
That being said, here are some tips for actually playing the game.
1) use cover - a lot. If you're going to shoot, brace up against cover
2) use your scope / iron sights a lot - the spray from holding down your fire button is much tighter and more accurate when zoomed in
3) look before you leap. manipulate the camera to look around corners before you run across open spaces
4) know when not to use cover - you can only learn this through experience, but hugging cover can restrict your arc of fire, often backing away from cover a bit will give you a better shot
5) don't camp. as soon as you set up a tent, you may as well put up a big flashing sign announcing your location.
6) if you're going around a corner where bad guys are, start firing before you get around the corner - chances are they'll still have their guns down and you'll get the drop on them (if your fire is accurate).