Performance problem with Camera.Render and many objects

I am working on a kind of "paint splatter" program. I instantiate a lot of tiny objects (10s of thousands) to create an effect on the screen. I am finding that performance is slowing down to an unacceptable level. This happens after the objects are drawn on the screen - Camera.Render continues to use an enormous amount of CPU, even though the objects are static. The objects are all the same prefab, colored and sized differently. Is there a way to optimize this?

 

Whenever large number of objects are to be drawn, expect lag. Just an idea: why not use particles?

 

Thank you, I'll think about whether particles can solve it. However I'm still wondering why this happens - does the engine re-draw the objects every frame? I would have thought that once they are on the screen, and static, that the CPU usage would drop.

 

1. Yes, the engine draws the object textures every frame, so you have to manually do the drawing "preservation". One way is to save periodically what you draw into a new texture and then set the texture so further drawing happens on it.
Here's a start point: http://docs.unity3d.com/ScriptReference/Camera-targetTexture.html
Note that rendering must be done every frame otherwise we wouldn't see it. The issue is drawing 10000 times or just 1 time per frame.
2. I guess an equally dragging factor is the number of instances in the scene.

Particles solves both problems, it just takes a bit to learn but it pays off big time (pun intended).

 

Thank you for your help!

 

Maybe the objects being sized different is breaking batching?