Borderlands 2 Lag Help Diagnostics

[tengarp]

My friend bought borderlands 2 and for a while he was able to run it fine, but recently he is experiencing major fps lag when playing the game.

His computer specs are:

CPU: AMD FX 4100 (non overclocked)

GPU: NVIDIA GTX 660 (non ti)

RAM: 16GB Crucial RAM 1600mhz

I think those are all the important parts. Anyway, he is experiencing lag and I am not entirely sure why. He has tried turning his graphics all the way down to the lowest settings , but it did not help. This leads me to think that it is a software problem, not hardware, but I do not properly know what software  in particular (gfx card drivers, game itself, etc.). Thus, I require assistance as to what he should do, such as re-install the game or some other suggestion, thanks.

[Morfy]

What is your CPU usage before playing the game? if you tryed with the graphics down, it's the processors fault, so look into your usage before and when playing the game and report back.

[tengarp]

What is your CPU usage before playing the game? if you tryed with the graphics down, it's the processors fault, so look into your usage before and when playing the game and report back.

Thanks, I'll tell my friend what you suggested and I'll tell you what the results are. Also, when you say look into the usage, do you mean by downloading a program such as coretemp and seeing the load and temps on the processor?

link:http://www.alcpu.com/CoreTemp/