Maximum performance for low power device, rendering benchmark

I have a low power device, an old Asus tablet from maybe 5-7 years ago. It plays games like hill climb racing 2 just fine and smooth.

I tried to profile how fast Unity works on this tablet. I created an empty scene with a camera, which moves horizontally at a slow speed. First I had a 3d object in the view, but then I decided to try without it completely.

So with absolutely nothing in the scene (well one directional light and the camera), drawing still takes a lot of time. And especially culling! What is up with this, am I missing something? The results look pretty much the same if I add my simple 3d object to the scene.

But this profiler shows the maximum performance Unity can provide? And constantly weird spikes in the profiler even though nothing is happening (except the camera scrolling horizontally).

I set the target frame rate to 60 (and when I had a FPS counter it fluctuated about between 54 and 60). Vsync is off (can it even be on on android?).

I tried to set all quality settings to low.

So where does this massive overhead come for rendering and doing nothing?