I've noticed that after a rocket launches, the FPS of my game drops about 5-10 FPS and the game becomes a lot more stuttery. A reload fixes the problem... until the next rocket launch. Save file is below, play until the end of the cycle, my rocket will have launched by then. My computer is more than capable of playing ONI, so this comes across as a bug to me. Also attached my dxdiag just to prove that it's not my system specs.
Play the save file.