Aside from the bad interpolation resulting in some laggy looking movement, There seems to be some kind of bug whereby the networked IK system just completely falls apart if an instance goes on too long, possibly with too many people being a factor.
All but 1 or 2 of the people in this clip are in VR, and a good chunk of them are in full body. They are all jittering around and all of them look like they are desktopping.
This happened twice to us. Once we moved to another world it cleared up, (leaving and rejoining the affected instance does not fix it, and in fact, upon leaving the instance, you get a disconnect error as you fade to black, and you spawn at your destination in the default grey robot man.) but after a while in the new world, the problem reared it's head again. People freezing in place and then teleporting and jittering around, and in desktop mode. (And a disconnect error on exit+grey robot man avatar on load in)