The Vulkan renderer doesn't seem to respect the V Sync Quality Settings properly. When you turn V Sync off in a Vulkan player the FPS will become capped, and when you turn it on, the FPS becomes uncapped.

Tested on 2018.2.0a5, 2018.1.0b12 and 2017.3f1.

1. Open the attached project
2. Build the project for Windows Standalone using Vulkan Graphics API
3. Boot the player. Make sure that the quality setting selected in the launcher is "Very Low" to maximise FPS
4. When the player launches, press Space to switch between V Sync Count setting 0 (off) and 1 (every v blank) and watch the FPS counter at the top left
5. When V Sync Count setting is 0 (off), the FPS is capped to your monitors refresh rate. When it is 1 (every v blank), the FPS is uncapped.