Low GPU usage and stutters

Copy paste of my Steam review:

Owned the original Insurgency. Still a great game, with Sandstorm the same idea got refined into a better game.

While this is a great game, it is still plagued with performance bugs and issues.

i7 4790
1080 Ti
SSD only system, no HDD in my PC

Game uses only 50-70% GPU even at the most demanding settings. Frame dips as severe as 50% drop can happen when firefight happens, consequently stutters. This can be alleviated if you get the video settings down to almost the minimum to achieve 100-200fps so dips and stutters are less impactful.

Have you tried tweaks from here?: https://www.reddit.com/r/insurgency/comments/acgp9m/tweaks_and_optimal_sandstorm_settings_for_higher/

I was able to remove the stuttering using tips from there.