High CPU Usage

[Twey]

I am attempting to run Amnesia on a Dell XPS 17 L702X with a GeForce GT 555M and an i7-2630QM processor. Amnesia played fine until yesterday, then all of a sudden it began running exceedingly slowly, even on the menus. I initially thought this was a graphics problem, so I tried it with both the Intel and NVIDIA halves of my Optimus GPU, but the issue persisted: I looked on top and found that Amnesia is actually taking up a large proportion (about 120%) of my CPU. I don't know how I could debug this problem.