I don’t know if this applies to other input methods as well, but I find that the out-of-the-box FreeCamera / UniversalCamera camera behave really poorly when dragged with the mouse.
As I drag the camera around, the sensitivity will occasionally plummet along either the x axis or the y axis, causing the camera to “stick” to the x or y axis. Sometimes it happens to both axis simultaneously and movement in any direction becomes very sluggish. If I set the camera inertia to 0, the problem goes away and it moves much smoother.
I notice this in the default playground scene and almost every time I go to move the camera in any playground using FreeCamera or UniversalCamera.
I’ve attempted to record the issue here. Note that I am holding down the left mouse button the whole time.