I am very sorry to hear that. Can you descibe what is actually happening? Given your listed problems, I am guessing low frame rate. If that's the case, try going to the settings and lowering the quality. Although, you did say it is hard to see, which happens when your quality is LOW (Light bouncing gets disabled). If your problem is low fps, try lowering the graphics ettings, if your problem is NOT low FPS, but rather the game being too dark, set your quality of to high (and insure you have turned on the lights, using a light switch on the wall).
Hope either of these solutions help, again, sorry to hear you are frustrated. It's pretty frustrating for me too, hearing people not being able to enjoy our games, because of a factor making it unplayable for them.