I forgot to ask you if your game has many effects in the scene, such as lights or particles and if you have many objects, such as many enemies or platforms. A game with 5 Atlasses could be the problem. The normal thing is that a game created with BB, has a maximum of 3 Atlasses, ideally only 1. The same with the size of the APK, check the music and lower the quality.
Optimize atlases. Find objects that all do the same things. Like ground, blocks etc. And use the Global Clones option (backup first as its undoable) what this does is instead of 15 blocks taking up memory as the game applies separate logic for each block seperatly, it only uses 1 block, then mirrors it out to the world. Greatly reducing lag.
