How to reproduce:

1. Open the attached project and "CharacterThirdPerson" scene in it.
2. Play the scene, run around and observe that movement/animation of character is smooth.
3. Select Edit -> Project Settings -> Time and set Time Scale to 100.
4. Leave the game playing for about 15-20 min (ensure the unity editor remains in focus on the desktop, otherwise the sample game will pause and the problem won't happen).
5. Set time scale back to 1, move character around again and notice animation and movement is now noticeably jittery and will never recover.

Reproducible: 5.2.4f1, 5.3.4p1, 5.3.5f1, 5.4.0b21