Sorry, I play on a old rig, and being around 10-20 FPS, I experience a slow down at some occasions, but no stutter. Perhaps this is due to video settings (there are video guides around to advise to turn off this or that setting), or a heavily modified environment.

As far as I read, the game loads the pre-generated world, and then apply any change you did prior when you move back to an area. This can be a strain if you built or terraformed a lot in this area.