too many variables...
1) Is this a new issue or something that just recently started happening? If it's a new issue it might be because you're using a 680M, if it just started happening it could be a driver issue, also it could be hardware failure.
2) What resolution are you running it at? Even at 1080p, full settings will definitely hurt game performance, especially for a mobile GPU.
3) What driver version are you using? Try either using the lastest WHQL drivers or the drivers that were released when the game was launched, they might of reduced game performance in the newer drivers in order to increase performance in newer games (happened to me with Arkham City and I have dual GTX 680s), alternatively your video drivers might of become corrupt, so a fresh install would alleviate that.
4) Have you checked your task manager to see if there are background programs running sucking up resources? This really shouldn't be an issue with an i7, however malware will eat your resources like no tomorrow.
5) Do you have a usage monitor application for your GPU to see if it's obtaining it's peek performance? It'll give you a good state of mind of where your GPU is at, ie if you get 15 fps while only being able to achieve a 30% load then it's clearly an issue worth investigating.
6) When was the last time you did a virus scan? Malware is like a gold digger, she'll take everything lol.
7) Are you plugged into the outlet when you're playing? Laptops with nVidia cards come with "optimus technology" meaning it'll use your iGPU when you're on battery.
8) Have you checked your power profiles? Certain laptops come with power management software, try shifting through it if you got it to try and force the GPU to work at full capacity for that particular title.
Also, for gaming, anything above 8gb is a mute point, however speed is relevant (not by much but 8gb at 2133 will provide better gameplay than 16gb at 1333 by maybe 5 fps)
What is that you omitted is:
1) resolution
2) OS
3) New or Recurring issue
4) Driver Version
5) Plugged in or unplugged (I'm giving you the benefit of the doubt and assuming it was plugged in)
6) Isolated issue or a persistent issue
There's more, but for this situation I don't think more is needed
Hope this helps, let us know if any of the above situations apply to you.