This is similar to what I was going to say. There are a couple of ways to define smoothness here. Most often it refers to frame timing and consistency between frames. The other is how close to real life the motion appears. For an extreme hypothetical, consider a locked 5 fps. It would be smooth in the former definition, but not smooth at all when it comes to motion. It’s this latter definition I’m referring to here.
30 fps locked has smooth frame times and is playable until it comes to camera panning. I can see noticeable jumps between frames. For example, consider a window pillar in the view. At a locked 30 fps on my 27" monitor, a fast horizontal camera pan with my Xbox controller can have the pillar jump about an inch each frame. That’s not the same as stuttering, it’s simply a limitation in how fast frames are rendered. Even slow pans are somewhat “jumpy.”
If I drop my settings so I can reach the 60 fps maximum my monitor is capable of, the movement of the pillar is closer to a smooth motion across the screen and not as jumpy. A higher frame rate would smooth things out even more, but it does become diminishing returns. In an ideal world where money is no option, I would love to have a monitor and system capable of playing about 90 fps for the sim. That seems to be about the sweet spot for my vision.