As a long time player, its probably settings. Which isn't your fault.

This shit is optimized like a snail in an f1 race, it just doesn't work. Turning clouds up is actually a viable way to get the game to run well, its super cpu bound, so if you turn up some settings it offloads some of that work to the gpu, freeing up some fps.

In my experience it plays way better now, but SC is a cranky bitch and its a free flight, never played a free flight that plays well, usually because players who don't know what they are doing clutter environments with busted ships, trash and more.