Sudden FPS drop in F.E.A.R (Logitech hardware)

Some users have noticed that they cannot play the game F.E.A.R. (or Condemned: Criminal Origins) with a high framerate, even though their machine is powerful enough for running 5 instances of the game simultaneously. Even weirder is the fact that the game will usually start with the correct framerate but will suddenly drop to 10-20 FPS, after some seconds or minutes. With such a low framerate, it gets difficult to play with pleasure.

You won't let Alma run away from you at 15 frames per second, will you?