Transparent Object Causes Lag. Which material that i should use for transparent object?

Hello everyone,

I have attached transparent textures to cube objects and i selected “Standart > Fade” material for them. I am using these transparent object as shadows of objects. Transparent objects decreases the frame rate. I can see that in Profiler as Camera.Render spikes. I have to use them in my scene but i think should choose the right material first. What kind of material type that i can use for them without loosing their transparency?

Thanks for your answers.

Any idea?