This is a minor issue present from 1.2 but now is going even worse.
In single player, any mission, start the game and go in controller options, it goes just fine.
But after one hour you cannot reach the same menu without waiting seconds, 8/9 seconds.
You will also loose the search by name functionality in the key/axis assignment UI.
The RAM ramp up from 4/5GB to more then 7GB.
As I wrote before I just updated system RAM from 8GB to 16GB, my 670M has 3GB dedicated and settings to LOW and FLAT shadows.
Intel Core i7-3610QM
NVIDIA GeForce GTX 670M - 3072 MB GDDR5
RAM 16GB DDR3-12800, 1600 MHz