FPS drop ingame?

[Volcros]

Hi, I recently built myself a new PC. I have an MSI GTX 1070 Gaming X, Intel I5 6600k, 16 gb DDR3 memory and a 1440p monitor. I am having an issue where when im ingame where my FPS will drop after about 15 mins. In BF1 for example I start with about 100 fps on ultra in the beginning and by the end of the game I will have about 47 fps. I have no idea why this is happening and I need a bit of help. If you need to ask me any questions please feel free to ask.

 

[Vanquisher71]

So, to start off, I use a website to help me see how well CPUs, GPUs, and RAM, run games on minimum and recommended settings (I've no real idea how useful it is, but I have no reason to suspect it's lying or untrustworthy and it seems pretty legit). It's called Game-debate.com, on there, it says your rig is 100%, in terms of running it, but your CPU is between 100 and 200 (on min and rec), while your GPU is good, and your RAM could do with a small upgrade for its recommended. You could also try visiting systemrequirementslab.com to see how well your rig can run BF1. If I had to guess, your CPU could do with a upgrade, or it could lag (assuming your talking about playing online).

(Do keep in mind BF1 is a newly released, high performance game I'm guessing has REALLY high requirements for playing on High settings with good frames)