Is that (see picture) too much for an android smartphone (i use nexu5) or have i a mistake in my scripting??
I get randomly between 30 and 40 fps and sometimes 15fps!
The project has scipts with about 4200 lines.
Another question: How can i debug methods like Update to ckeck how much time they take?
Performance on the mobile platform is quite a difficult subject. Particular attention should be paid to the alpha blend on your textures. It is impossible to move large pieces of mesh every frame, like mountains in the background. Only need to use the skybox.
There may be many reasons why your FPS goes to zero. Need to see the project to understand the problem.
The statistics picture shows 53.6 FPS, with 62 Draw Calls, 22.1K Verts. That’s not bad performance as such. However, you must take into account that you are running the app in a Nexus 5, which has Quad-core 2.3 GHz Krait 400 CPU (similar to a quad Cortex A15 CPU), and Adreno 330 GPU. If you want your app to run in as many devices as practically possible, you should consider how your app would run on medium (and probably low) spec devices too. I personally prefer to leave out low end devices, so I have a personal minimum spec target device of 1GHz single core Cortex A9 CPU, with Adreno 200 GPU. Your target devices is a design decision you have to make, which of course depends also on the kind of app/game you want to make.
So, although your statistics picture shows 53.6 FPS, while running on a Nexus 5, the statistics for your app, taken at the same instance, would probably be quite lower, even 5 or 10 FPS, if the app run on the example medium spec device I mentioned above.
You also mentioned that sometimes the FPS drops to 15 FPS. You can imagine what would happen to the FPS, at that instance of the game, if it run on a medium end device…
I provide some links below, which refer to performance considerations for mobile devices: