Beginner: Wrong workflow? 8x8x8 LED Cube to complex Total beginner here - I hope you guys can help me :)

So I want to make a 3D representation of my LED Cube. It consists of 512 LEDs (8x8x8). I think it should be pretty simple... So I started reading a Tutorial and now I just created the 3D LED cube. But the performance seems pretty bad - thats why I think I am using Blender wrong :)



My Workflow:
I deleted the standard scene and then added a UV Sphere
I reduced the segments and Rings to 12 and reduced the size to 0.25.
I hoped that this would make the performance better (I want to export it to a .obj file and use it in a C# Program).
Then I duplicated the singe LED and created a row, changed the position of each new LED. When the row was done I created an 8x8 LED side by duplicating the row 7 times. Then I duplicated the first side 7 times to get my 8x8x8 cube. 

My object looks like this:

I see that the verts/edges/faces count is pretty high - I assume this is bad for my performance. Is there a better workflow for my little project that results in a better performance? My exported Object is 4.91 MB big - seems a little big for a simple cube or is this ok?

Sorry but I would really appreciate any help I can get :)
I honestly see no problem with this, there is not much you can do except
for making the mesh at a lower resolution, 
you do not mention what engine you are using this in, but one option might be to look in the engine you use, then see if it supports instancing of meshes which then can have separate materials assigned (I assume you are assigning materials to the different LED's during runtime.).

The you only export one LED, then create it all by code (instance,move the instance, assign materials and so on). That way the mesh memory is kept low, because it will only load 1 LED mesh.

But again - this scene is not big at all compared to other game content that typically exists in a scene.