Foliage on Mobile devices performance Question

Hi there, i have figured out that the foliage Tool on mobile devices makes a huge difference to what it does on PC.

I´ve paintet some gras on a Mesh and startet the game on a Nexus 4, nexus 5 and Galaxy Tab 4.0 Device.

On all devices the FPS and Draws shrink very heavily when i get the foliage Actors in my focus.
It is like every singe foliage creates one draw call on mobile.

FPS without foliages in Focus: 40 - 50 FPS
FPS with foliages in Focus: 3 - 5 FPS

Please help me out, do i have to let off of foliages for mobile and make a single mesh for things like gras on the ground or is there another thing that i have to consider?

no idea for this?