because the amount of memory of your graphics card is a lot less important than the actual capabilities of the GPU. most people buy graphics cards simply by looking at the amount of memory but if the GPU is crap, no matter how much memory it has, it still won't run anything fast.
If you do have a decent GPU, than maybe you've simply overdone it on the game settings. remember, it's still a laptop... no matter how the GPU is named, a mobile gtx 550 for example is nowhere near its desktop counterpart.
finally there is the question of how well your laptop is set up to begin with. maybe too loaded with software to run well?
your looking at minimum settings on games like bf3, skyrim medium high, crysis 2 low medium. having 2 gigs of vram wont really help on your system until you attach a bigger screen via external output. you could have saved quite a bit of money and not lost any performance by getting the 1gig model... basically they have sold you a turkey in that they counted on you not knowing that you didnt need it.
settings that you will have to turn off in every game are things like msaa, fxaa,hbao,ssao soft shadows and depth of field... all of of these settings will have varying impacts on frame rates from a small medium impact to very large (hbao/ssao)