Steps to reproduce:

1. Open attached project
2. Open scene "test" and run it
3. Press C to spawn Rigidbody with Continuous collision
4. After hitting terrain it will do some flips and the slow down for few seconds

Additional steps:
5. Press D to spawn Discrete Rigidbody
6. Notice that there's no slow down like in step 4

Note: Not reproducible with Discrete Collision Detection

Reproduced with: 5.3.1f1, 5.4.2f1, 5.5.0b8