Dynamic batching slows down?

Hello

I have a test scene with 10'000 objects (spheres), each object has 5 lod levels.
The Lod_0 object has 610 tris.
The Lod_1 object has 384 tris.
The dynamic batching doesn't work for Lod_0, but for all other lods it works.
All objects of the same lod have the same material and mesh, there's no point light or shadow in the scene.

When I activate Lod_1 for all objects I have a scene with:
- 10'000 draw calls (0 saved by batching)
- 6.1 mio triangles
- 32.4fps (cpu: 30ms, gpu: 9.4ms)

When I activate Lod_1 for all objects I have a scene with:
- 442 draw calls (9658 saved by batching)
- 3.8 mio triangles
- 11.3 fps (cpu: 85ms, gpu: 69ms)

So you can see, dynamic batching works and reduces the draw calls significantly, but it slows the game down.
The objects do not move, share all the same size (they are in fact exact copies of each other) and there's nothing to break the dynamic batching.

This behaviour is a big isue for me, because I need a testscene with that many objects for a demo of my asset...

Has somebody an idea what the problem could be?
If yes, I would be very happe. ;)

If not, can somebody confirm this isue?
Then I will create a bug report.

Greetings
Chillersanim