Reproduction steps:
1. Open the attached project "StutterTest.zip";
2. Build the scene for iOS;
3. Launch the project on the device;
4. Observe the Rigidbodies movement.

Expected results: both of cubes are moving silky smooth just like in the Editor.
Actual result: the cube which is moved using MovePosition stutters while moving.

Reproduced on: 2017.2.0b7, 2017.2.3p1, 2017.4.5f1, 2018.1.4f1, 2018.2.0b5, 2018.3.0a1.
Not reproduced on 2017.2.0b6 or lower.

Reproduced on both iPhone 7 (iOS 10.3) and iPhone 5s (iOS 9.3.3).