Unfortunatly what you suggested was not the culprit. However I did a bit more testing and found the following results: With very sever weather: SMP enabled: Higher FPS, but longer and more frequent stutters . SMP disabled: Lower FPS, but relativly shorter stutters. With a perfectly clear sky: SMP enabled: FPS capped at 60, still stutters though not as bad as the above section. SMP disabled: FPS slightly lower 55 ish, but stutters are almost eliminated. Clearly loading terrain and cloud data is causing the issue. Though I'm not sure what can be done to address it.