i3-3217u

The processor lists as having Intel HD Graphics onboard--make sure that your system is set to run the game on the nVidia card.

It's also on the lower end of the scale for an i-Series CPU (1.8GHz, dual core), so you may be running up against some CPU limitations when trying to manage highly congested areas. Scored 2273 and ranked 664 on the Passmark lists... beaten by a 6 year old C2D E8500 at it's stock speeds.
http://www.passmark.com/cpubenchmark...1.80GHz&id=764

So, you may need to tweak out your settings a bit--reduce physics for others and such. Shadows may need to be lowered or even shut off as well. There's a lot that has to be managed by the CPU when in the big crowds--it's not just the GPU performance index you have to worry about with this game. But, you may want to go in and make sure your card's settings are all on either Performance settings or on Application Control. Once you get things tweaked out for the best frame rate, then go back in and increase the quality items if you have enough headroom in your FPS.