Performance and memory using sprites

Hello,

i was wondering whether it is better to have on big texture combining all graphics and use this as a spritesheet (tiling+offset) or have many textures.

I added this graphic below to clarify my problem:

Does one big spritesheet hit the performance, when different gameobjects use it as a texture and even some gameobjects use the same graphic on the spritesheet? Is it a good idea, to use on big spritesheet on ios platform as a shared material or would this blast the ram?

Thanks for your help, Thomas