Bug: Extremely low frame rate when using TextureRenderTarget2D for spectator

I tried to implement a spectator for my app by using TextureRenderTarget2D and discovered a weird bug.

Everything works fine in the editor, BUT as soon as I package my project the frame rate drops really low (<15fps, sometimes less than 5 fps).

This is a bug related to Oculus somehow, because when I try running the packaged project with my HTC Vive everything works as expected.

Steps to reproduce:

1. Start a new project with starter content.
2. Check "Start in VR" in project settings.
3. Add a TextureRenderTarget2D to the project, set the size to 1920x1080.
4. Open level blueprint and add the following to "Begin Play":
   - "Set spectator screen mode" and set it to "Texture"
   - "Set spectator screen texture" and set it to our TextureRenderTarget.
5. Add a "SceneCapture2D" and set its target texture to our TextureRenderTarget and its capture source to "Final color"
6. Package the project

The frame rate for the packaged project will be very low. I becomes very visible when turning the head from side to side.

I have reported the bug to Epic, but the bug have regretfully been placed as a low priority backlog issue. Maybe someone at Oculus could look at it, since it seems that only Oculus Rift devices that is affected.

Bug at Unreals Issue tracker: https://issues.unrealengine.com/issue/UE-70352

Discussion at Answers: https://answers.unrealengine.com/questions/792290/view.html