Startup takes too long

Hello, i have been developing a new project for Android and it takes over 16 seconds to load the scene. It boots fine, but after the splash screen, the screen goes black and takes too long to load. I made a bootstrap scene and added a loading script but it took the full 16 seconds to take to the bootstrap scene, THEN it took less than half a second to load the actual scene.

The game has only 1 scene and is less than 120 megabytes. I worked on many android games before and all of them boot just fine, what's wrong? I tried searching for this problem around and the only (few) people who had this problem seemed to have either unoptimized scripting or tons of textures, which is not my case. Game is 2D.

 

Does this issue occur on other devices as well, or is it specific to one only?

Does the game make use of the Resources folder?

https://unity3d.com/learn/tutorials/topics/best-practices/resources-folder

Perhaps slow code runs via [RuntimeInitializeOnLoad]?
https://docs.unity3d.com/ScriptReference/RuntimeInitializeOnLoadMethodAttribute-ctor.html

 

My game does make use of the resource folder but it only has a few scripts and important files. No code using RuntimeInitializeOnLoad. Also, happens on other devices.