Particle System & Pointlights over Sprites, Performance issues help

Hi all guys! I am developing a 2d platformer game with unity and recently we decided to add some cool light effects. Right now we want to achieve a cool fireflies effect. We use the particle system with a script that generates a point light for every particle and reuses it after the particle is destroyed, assigning it to the new particle. We had to set the render mode of those lights to Important, because otherwise our backgorund ( which is a large sprite tiled over and over, like many platformers around) would be light only on corners and then nothing ( that's what important render mode , or pixel render mode is :P )

We tried to build the scene for the Iphone 6, just perfect, 60 fps perfect. But when we try to build it for the Iphone 5, things goes bad and the game slows down very much when there are more than 3 point lights on the screen. actually our scene , takes no more than 60 draw calls, and 1k tris, and 700 verts.

Any suggestions on how to improve performances, obtaining the same cool effect?? (right now the point lights attached to each "firefly" in the culling mask illuminates everything that passes under them , from the background, to the player, to the monsters etc) Any suggestion is welcome!!! :)

I tried to check the impact of point lights on the mobile performances also to enable just 3 point lights (without particle system) that moves from a point to another with the animation. Same problem, the performance on iphone 5 and slower devices are terrible, especially when the player passes under those lights.

I don't know if there is a way to achieve the same effect with lightmapping. if there is one, it would be great! :)

could it be a shader problem??