I do think something is wrong here. I tested your save and also am suffering extremely poor performance on my rig, and it should be able to handle this fine:
I usually play on high profile, but put it down to the lowest for this save. I am able to suck about 20fps out of it and get full game speed. On high profile it averages 5fps and is about half gamespeed.
Is something up with the sound? I usually don't play with warheads or any advanced stuff but some of the EMPs and stuff going off are creating an awful noise in my headphones that could resemble static or something like that. It doesn't sound very nice either way. It could just be the FPS lag causing this but I wouldn't know.
SPECS:
Windows 7 64 bit
NVIDIA GeForce GTX 760
AMD FX 8150, @3.6Ghz
8GB ram
I am also running on an SSD
As you can see, not top of the line rig, but definitely mid-high end rig that has no problem playing any of the latest games close to maxed out/high settings.