I’ve been able to tweak my options to get up to 90% GPU usage.
The goal is to get the ‘Limited By’ metric in Dev Mode FPS Display to rapidly switch between ‘Main Thread’ and ‘GPU.’
If my CPU intensive settings (traffic, TLOD, OLOD, and some others) cause it to always display ‘Limited By Main Thread’ I’ll back them down and increase the GPU intensive tasks (like antialiasing, render scaling, volumetric clouds, and others.)
When I see ‘Limited By’ rapidly flickering, I know I’ve hit the sweet spot.
Here’s an older thread that goes into great details about all the different graphics options.