How to reproduce:
1. Open Unity, create or open a project
2. Move the Scene View camera a single direction then quickly reverse to the opposite direction
3. Observe the pause in movement as the direction is reversed

Expected result: The camera shifts movement directions smoothly
Actual result: The camera stops for a moment before resuming movement in the new direction

Reproducible with: 5.6.0a1, 5.6.6f1, 2017.1.3p3, 2017.2.2p3, 2017.3.2f1, 2017.4.1f1, 2018.1.0f1, 2018.2.0a5
Not reproducible with: 2018.2.0a6, 2018.2.0b1

Notes: Moving the Scene View camera by holding down right click and using WASD or by using arrow keys reproduces the issue. Rebinding camera movement keys still reproduces the issue.

Fixed in: 2018.2.0a6