Space Navigator appears to have a sampling-rate issue / un-real-time mismatch with Blender.
Blender responds quickly to SN inputs, and keeps responding long after the user has let go of the mouse completely.
This causes perceptual/temporal skew and mismatch between what a user thinks he/she is controlling and what is really happening, which is evident as Blender continues to play out 3D locator actions after the user has quit interacting with the mouse. There appears to be no setting to adjust Blenders mouse sampling rate more coarsely, so it won’t ‘get behind’ in trying to keep rendering too-fine temporal increments of future-past scenes which accumulate to be some seconds distant from wall-clock time.
A workaround of only moving the mouse in tiny amounts for short periods of time and letting go of it completely for intervals so Blender can catch up is somewhat interactively frustrating. The degree of the time-mismatch appears platform and OS -dependent; ie. this problem is not manifest on my MBP under Snow Leopard with 2.69, but apparently 2.73 under Mountain Lion on the same laptop runs imperceptibly a bit slower. This is not a problem with any except the 3D mouse locator.