Framerate drops severely when disabling Oculus XR and re-enabling it

Unity Version: 2018.2.5f1
Oculus Unity SDK: OVR Plugin Version 1.32.0
Framerate drops severely when disabling Oculus XR and re-enabling it.

1. What happened
Using Oculus, if you enable XR then disable XR, when you re-enable XR the frame rate drops significantly. The more times you enter and exit VR, the worse the issue becomes.

2. How we can reproduce it using the example you attached
Steps to Repro: 
1. Open Sample Project titled "Oculus_VR_FPS_Degeneration"
2. Open Scene "SampleScene.unity"
3. Press play
4. Press "Up" key to enable XRSettings. Take note that the framerate is stable.
5. Press "Down" key to disable XRSettings.
6. Press "Up" key again to enable XRSettings.

Expected Results: Unity should return to VR at a stable framerate.

Actual Results: Unity experiences a period of deteriorated frame rate.

Tested and reproduced on: Unity 2018.2.5f1 & Unity 2018.2.1f1
Unable to reproduce in: Unity 2018.1.9f1

License type: Pro