Note: this issue does not involve play mode
To reproduce:
1. Open project MecanimTute
2. Open scene Main
3. Select terreno in scene
4. Set it's detail distance to 250 (basically this should make navigating in the editor slow)
5. Try moving/rotating the view in the scene - it should take some time before you make an action and for it to actually happen. If you make a couple of movements in a short period, after the initial delay they don't "hiccup" anymore, but if you move and then wait for a few seconds without doing anything - the delay returns.
6. The weird part: Open quality settings (but don't change anything, just keep them open). Try moving in the scene again - there is an initial delay, but if you wait for a few seconds, it does not return. The delay is no longer present and you can navigate in the scene without any "hiccups"

Changing the quality settings does not seem to affect this, it's mainly just because the quality settings window is open.