Performance grinding to a halt

Performance takes a real hit for me. Halfway through a level my framerate plummets until there is visible, jarringly jerky motions of the camera, creatures, enemies, etc.

Trying to drop an imprisoned enemy into my torture chamber is becoming difficult because of the framerate/lag. You think your Hand Of Evil is hovering over the torture device, but once you click and the game catches up with everything, your mouse pointer was actually three rooms to the left or right. You can imagine how frustrating this is. The game progresses for a second, then halts for a second, then progresses, then halts, constantly struggling to catch up with itself.

I haven't tried this in multiplayer.

My specs are below:

CPU: Intel Core i7 4790K @ 4.00GHz

RAM: 16GB DDR 3 @ 799MHz

OS: Windows 7 Home Premium 64-bit SP1

GPU: GeForce GTX 1070 4GB

Please find my output log attached.

Output Log

I've tried lowering the graphics quality, lower resolution, etc., etc. but the game just ends up staggering after a while. Grinding through the main campaign became a chore on the later, larger levels. I am currently trying to play Heart of Gold but the performance has put me off.