I’m making a 2D Android game and when I test my game on a physical device, it takes a pretty long time to start.
I can’t seem to track down the exact cause because when I click on the app icon, a black screen appears for about 15 seconds then the unity logo appears. After the unity logo fades out, it waits another 5 seconds, then the first scene appears.
This is odd behavior that I’ve never experienced before.
What could be causing this?
How can I speed up the loading time?
Here are seven optimizations you can take a look at:
1.) Have one simple unity loading scene, with which you handle the loading of all other scenes. There you can easily add custom animations/progress bars or other logic and you can be sure, that loading the first scne does not take forever
2.) Switch your build target from Mono to IL2CPP if you haven’t done that already. I have a strong loading time boost for IL2CPP on android. Oftentimes I still use mono for development, since it just is quicker in building the app.
3.) Check your Preloaded Assets Array in Project Settings->Player ->Other Settings. All those assets will be loaded before anything else happens. Especially shaders can take a long time there. I would recommend not to use that feature (or just for small or really essential assets), but rather handle the loading in your simple first scene.
4.) Shader compile times can be really high on mobile. I do know this from iOS, but I assume it is the same for android. Avoid using too many shaders and shader variants. You can track the shaders you use by Going to Project Settings->Graphics. Just hit clear once, and then run your game. You can sace the tracked shaders to a ShaderVariantCollection to analyze the shaders that are used.
5.) You can track your improvements in loading times with Time.realtimeSinceStartup, this gives you the time from the very first second you hit the app icon. Another solution would be to make screen captures to measure the startup time.
6.) Also profile on device with the unity profiler to see what takes time to load and make sure to reboot your device every once in a while, since there might still be stuff in GPU memory, even if the app was killed (At least that’s the case for iOS).
7.) (Added later for future readers) Test your build with a normal build (No development Build) to see if the problem occurs tehre as well. Connecting to the profiler and enabling all debugging features can take quite some time.
Happy optimizing 
Thanks for the help!
I’ve changed the scripting backend to IL2CPP and this basically eliminated the long loading problem.
On the other hand, I was wondering if you could help me with two other issues I’m having in my game?
1.) I’m having issues with enormous physics spikes at the beginnings of every level.
2.) Camera renderer ‘clear’ is hogging every frame. I don’t know what it does, nor how to fix it…
I could really use some advice about these two issues I’m having, of course, If you know anything about it.
Thanks again
[Update]: This is important for anyone having similar problems! 
Just found out that the main reason for the black screen lasting a long time when the game was launched is because in my build settings I had ‘Autoconnected Profiler’ turned on. Turns out, this feature allows you to profile your game wirelessly from a physical device as long as your computer and test device were connected to the same network.
If the internet connection between the two devices was poor, or if they were not connected to the same network, the game took extra long to load because the Android device could not establish a connection to the profiler, or it took longer than normal to establish the connection.
To fix this, make sure the two devices are connected to the same network with a strong connection, or turn off ‘Autoconnected Profiler’ in the build settings. The only difference is that turning off ‘Autoconnected Profiler’ will give you more accurate loading time.
I won’t dive too much into detail, just a few ideas. For more indepth discussion I recommend opening a thread for your problems in the fitting subforums.
1.) Hadn’t had the problem so far, but you could try enable multithreading for your Physics2D. Other than that, if it’s just a 10ms spike that happens every time you load a level, you could easily hide that through UI, or whatever seems fitting, right?
2.) I think I saw that problem for others, that used more than one camera. Maybe experiment with the clear flags of your camera. Seems like something is blocking the clear somehow.
Hey if someone happens to still have a long loading time before the game launches and you already tested all the solutions above then maybe you have many audio files in your project, you should select all your Audio Files and uncheck Preload. Or uncheck it for some of them at least
yes quite true, in that case you better tick “load in background”
Can’t agree more with the last 2 posts. I reduced my game loading time by around 4 just doing that.
As a side not, for me what worked was to leave the “Preload Audio Data” ticked, but to ALSO tick the “Load in background” (important to leave them both ticked).
This post explains quite well the difference between all options in case you are curious about it :
Summary :
Man I had tried everything, this was my issue. thank you for the post.
In my case, it was too many HD mesh colliders has to be generated on the phone when the game start, once I converted them to box collider, loading become instance.
