Friend, your CPU is bottleneck for this game.
I had same issue with my i5 4670k, it was 100% loaded, every time, with any settings.
To resolve this issue I overclocked CPU to 4 GHz in BIOS and also set 60 fps limit in the game.
Now I have stable 60 fps without drops on all maps with almost all settings are maxed in the game, even the shadows. (resolution 2560x1080)
CPU load varies between 50% and 100% (btw, smoke effect is very heavy for CPU) and GPU load is ~50%, I have RTX 2070.
Also, try to delete all config files. It helped me to resolve the performance issue with the shadows after the last update.
75 fps cap limit is missing in video options. There is 30, 60, 90, etc... How about adding 75?
My monitor is 75 hz, and I prefer to use the fps limit instead VSync.
I know it's possible to change this in the game config file, but it will be nice to have it in the game options.
Thank you for the great game!