Random low FPS and GPU usage until I restart the game.

I don’t know what causing it, it happens at any times, I’ve had it happen just freeroaming, online racing, in a loading screen, while painting.
When it starts it’ll drop my frames to 0-20, and GPU usage goes down to 0-30% for a little bit and then it’s back to normal for a bit, goes back to low fps and so on until I restart the game.

Me and my buddy have had this problem ever since we bought it a week or 2 after launch. I can play the game for a bit smoothly but after a while the game becomes a stuttering mess and my gpu usage drops anywhere from 10% to 2% when it happens. Then I have restart it if I want to play again. And if I decide to beeline it through a field and I’m going too fast sometimes the stuttering gets bad then my textures don’t load and I get the low streaming bandwidth message.