Question Mixed Relality Portal - OpenXR Developer Tools for Windows Mixed Reality - Render scale

Hello,

We just migrated our core game to openXR and we are testing both Mixed Reality Portal and SteamVR as OpenXR Active Runtime.

We have G1 and G2 headset. For G2, we need to change the render scale to have a good performance.
We are using for this "OpenXR Developer Tools" (when not using SteamVR).

I have several questions:
- To begin with, at a time, we were using "OpenXR pour Windows Mixed Reality". It seems that this app has disappear and is not needed anymore?
- Is there a differences between changing the Headset rendering resolution using SteamVR or Mixed Reality Portal. We have performances differences (when using the same resulting resolution).

For OpenXR Developer Tools, is there somewhere a documentation.
Due to some performance issue, we want to be sure we use it correctly.
In some specific spot in our game, the FPS go down to 45 fps (no issue with SteamVR).

In OpenXR Developer Tools:
- What is the meaning of Motion reprojection? "Disabled" will crash our app. What the differences between automatic and Always on.
- What is the meaning of Jiggle view rotations
- "Custom render scale" --> does it change the render scale of the headset lens? Is there an additional specific condition with this setting?
- When changing a setting, do we need to restart something (Mixed Reality Portal for instance...) to apply the changes?

Thank in advance for your help.

Alex