Question GPU causing fps drops in games like Rust?

100% GPU usage while gaming is what everyone should expect. It means you are at full gaming potential for your system (relatively speaking.) Rust is not a very optimized game, so you will likely have frame drops with any GPU. The GPU will just determine what frame rate you will be when it is dropping.

Although... it does look like you are nearly maxing out your video memory. What resolution and game settings are you playing at? Try reducing one of the settings that eats up your video memory. Maxing out video memory is one thing that will cause unnecessary frame rate drops.