It's interesting, but I've recently started encountering this same issue. I didn't have it before, but it's a problem now. Not entirely sure what caused this to happen, is there some windows system tool I can use to see what changes I've made to my system (installs / programs / services) in the past 2 weeks?
My specs are the following:
Nvidia geforce 670
Win 7 64-bit
SSD + HDD
I've tried the game on SSD, but it doesn't seem to help. My current performance is similar/identical to that of the second video, and the game used to work fine 1-2 weeks ago.