It could also be a software issue. Try restarting your computer and re running the game. Some parts of the game may take a harder hit on your computer than others. Did you do a fresh install?
I just ordered a new motherboard (MSI Z97 Krait Edition) and it looks extremely good in my PC. I ordered this because my last motherboard had several bent pins that iBuyPower was so generous to give to me and I would have to have any CPU that I order installed customly, and my computer performance was extremely effected by this. I put my CPU in (4790k) right when I got the motherboard and it worked perfectly. And the next day, I woke up and started my wonderful PC up, and from last night to this morning, I dropped an average of 30 frames on Arma 3 (from average of 70FPS to about 25-40FPS). This was the exact same thing that happened to me on my last motherboard. I don't want to take the CPU out to check for bent pins because I might have to take it in for the 5th time if I have another one . Is there anything besides a bent pin that could be going on here?
It could also be a software issue. Try restarting your computer and re running the game. Some parts of the game may take a harder hit on your computer than others. Did you do a fresh install?
Your power supply might have a hard time handeling the CPU.