If you reduce the time speed the movements of platforms objects are still smooth but a physic object movement is lagget and you can see the object teleporting.
Can we see your code? You should never see an object teleport.
Probably it has to do with the “time step” commonly used by physics engines, not 100% synced with the time scale or a limited number of steps due to performance…
The physic engine shoud be running at 60 fps. 
I think I’m having a similar problem. Physics object falling, without any event forces affecting it, with camera following the red reticle:
The camera adopted the janking if it is focused on the object and then other objects (like the green reticles that trail the object) start to jank:
The janking also happens when the object is affected by forces, but the janking becomes more random then. Please advise whether this is a problem of the engine or on my end.
Full project:
dl.dropboxusercontent.com/u/722 … 200.01.zip
Forcing a higher refresh rate increases rate of janking. Janking distance increases at higher speed. I tried a lot of other stuff to fix this, including changing around a lot of the physics variables, but to no avail. At higher game timescales (around 5) the problem is no longer noticeable.
How to open .gdg files?
With GD4 only. You can download it on the website.