When my focus is off-planet on a moon building stuff, the units and buildings from the main planet are rendered. If there is a lot of combat ongoing on the planet, my FPS drops down to about zero for minutes. Could you provide an option to toggle drawing units on other planets that aren't the current focus? A wireframe of the planet would be even better (from a perf standpoint). Also, having 10+ planes on patrol (or moving) cause my system to lag right out. I hardly use planes now because the effect is so brutal.
In the settings menu for UI there is an option called something like "only draw what is visible". This gave a big perf increase on my I7 2600k/7950.