Does depth only camera cannot apply image-effects?

Hi there.

I’m working with a aircraft game that the camera has a very big far clipping plane which is reaching 10240. The model of terrain have some artifacts on junction point,so I added a depth only camera to show nearly space(called aircraft camera then) and added the near clipping plane of the previous camera to show the terrain(called terrain camera then),then the artifacts disappeared.

The aircraft camera’s depth is always bigger then terrain camera,with near clipping plane 0.5,far clipping plane 100,the same position and rotation with terrain camera.

The terrain camera with near clipping plane 100,far clipping plane 10240.

Then,I want to add a bloom effect to the screen. At first I add the bloom script to the terrain camera,it work well on Unity Editor and Android devices,but only terrain camera is bloomed and the aircraft camera is out of bloom. Then I replace the bloom script to aircraft camera, everything looks well on the Unity Editor,whole screen is bloomed.

Now here is the problem:

When I build it to Android devices, the FPS down to 3. The game almost crashed.

Can anybody tell me what this is all about? Is anything I did wrong?

Really needs your help,thanks!

Anybody?