I am pretty sure that you are having memory issues (See the logs, near the bottom)
Download some program that reads our your PC set up and clock rates and shit (Think CPU-Z does that)
See if it shows that you have less RAM than you remember to have (Maybe a RAM stick fried)
Or if your GPU clock rate is significantly lower than it should be. (While idling on the desktop, and once again while running the game)
Also checking your fans is always a good thing to do. Make sure they are clean and working properly.
Checking your GPU temperature is a good idea as well. (While idling on the desktop, and once again while running the game)
That is about all I can think of right now, if anything else comes to my mind I will let you know. (Maybe someone more competent will see this thread as well)