Unity 2D many Sprites performance on Mobile - Sprite Atlas

In my scene :

There are 4 parallax layers, one platform layer and one characters layers (there is only one character for now).

All parallax layer sprites are in single 2K sprite.

I am using perspective camera for parallax effect.

It is 2D platformer game.

I am using Unity 2017.1 engine, created Sprite Atlas using Unity Engine only.

Stats are :
8 batches, 33 Saved by batching
9 Set pass calls
Less than 700 tris and 1000 vertices

If I disable all the parallax layers FPS increase to 60 on Android platform
and with layers enabled FPS drops to 30 fps.

My doubt : New Sprite Atlas feature of Android might not be working on Android ?

Can someone please guide me how can I improve the performance with all 4 parallax layers on.