Performance issues on VR 4.21

I created a VR game for the Oculus store which is using simple Cartoonish asset.
But the app is not running on 90hz. Even in empty levels. I optimized probably everything:

What I did:

Static lightsource,

Only Static lighting,

enabled Forward shading,

enabled Instanced Stereo,

changed from TemporalAA to MSAA,

enabled Adaptive Pixel Density,

disabled main Post Process features (Bloom, Lensflare),

disabled Composite Depth (caused z-fighting on AMD),

made no gameplay use of Event tick,

Smooth FPS is off and min. desired frame rates by 90,

Does anyone got an idea what I could do? Is it a bug?