After seeing too many late games have the FPS slow to a crawl (even for solo play), I did some investigating. Here are some proven solutions: https://www.reddit.com/r/Stellaris/comments/4im9q2/how_i_improved_my_framerate_by_40_fps/ The biggest changes seem to come from turning Multisampling to ZERO in the vanilla game settings. Keep in mind, however, that this makes the map boards look kind of crummy. Interestingly, turning graphics to Low seemed to not have much of an effect on visual quality as far as I could tell. Here are the graphic settings I use: (you can see the blurry effect on map borders from low Multisampling, but I got an extra 10 FPS easy from doing this). Game settings are also a factor. Based on various sources of community feedback: Last I checked, Stellaris isn't optimized for multicore CPUs (still using 32-bit?). To prevent deceleration you need to reduce CPU load. Heavy load is caused by: Big fleets Many planets and large numbers of pops AI empires Fleet movement Building planning Much of the above can be controlled by two factors: Reduce number of habitable worlds. You can easily reduce habitable worlds by 50% without noticing any significant impact on vanilla gameplay. Less habitable worlds means slower build up of fleets and less CPU occupied with calculations for colonies. Reduce size of map. Smaller maps have less AI factions and, as a result, generally have less stuff on the map to calculate.
