Which simulation are you running, what time step are you doing and what are your system specs?
If its the one that Ubox2 opens with, moving around is fine, however the timestep goes red if I go higher than 5 secs per second.
If its the solar system with moons sim, that one lags pretty badly when I move the view around. Even scrolling the menu is laggy. Then again, my comp is 5+ years old, 6 I think.
In the rift space category and solar system sim (which is pretty incomplete and everything is trying to orbit Jupiter) the orbits are a bit laggy but the movement is smooth.