FPS Issues

Anyone else having FPS issues with this game? I have a GTX 970m and it always starts up fine when I first boot up the game. Goes right to my FPS cap. Then after playing for a while, FPS starts dropping to less than 30. This happens regardless of what graphics settings I put it on which is weird. I noticed when the FPS starts dropping, the game's GPU usage in task manager noticeably drops. When the game starts and the FPS is good, GPU runs at 99% usage. When FPS starts dropping, GPU usage drops to 50% or less. Anyone know how to fix this issue? Is there a way to keep the game using max GPU?