Yh the 80% GPU usage might be because the CPU is being "limited" through the engine by some bug or whatever, funny enough ive noticed this issue as well. my CPU usage constantly regardless of frame rate sits around 35-38% on my 3700x, but I have tested the cvar setting and this made no difference to frame rates but did increase CPU usage. Even when testing at 720p frame rates barely increase but CPU usage in reality should increase as you lower res/settings as its more CPU bound than GPU bound but it doesnt increase CPU usage anywhere. so maybe its actually a CPU utilization issue, would need more people to confirm as ive seen some reports of "high cpu usage" as well.