Memory leaks are a bitch. I've spent days trying to find them in the past only to find it's a fault in the compiler and you have to rewrite the code to get around it :/
Looks pretty sweet though :)

:( Turns out it's a memory leak of some kind. It's a sandbox game and you can create your own missions. Now the more enemy units you add along with preset paths and how to act (evade, engage only when fired upon, free to fire, etc) fills up the memory real fast. And I played my mission over and over.
At the beginning (first play) the v-ram is 'only' 6GB but if you replay enough it just fills up. Great engine by Bohemia. /s

Had to pause the game (goes to a pop-up menu).

It's only using 10% of GPU?