Must be graphics card related.
Out of the box, SR2 was UNPLAYABLE for me - the framerate was just too horrible. With the first patch, I didn’t have serious problems.
There was SLIGHT stuttering occasionally, and of course the graphics didn’t look all that good, but otherwise - no issues for me.
I’m still waiting for the assembly line of mods they announced to roll out for SR3, though… (Yeah, I’m aware of the actual announcements and the fact that the loads of mods ain’t coming.)