I am getting random extreme framerate drops. It can happen when even nobody is in jet suits. The game runs fine then *bam* 1-2 fps for a random amount of time, then it goes back to normal. I am used to the game chugging with the large bases I build, but not this severely. I will upload a save file if I can but it's 15MB even compressed. This only started happening after the latest update.
Just load the game and wait for the drops to happen. Idle or doing something it doesn't matter.