Need help: Instantiating prefab or use GUITexture? Or any alternative?

Here's what I'm trying to do: The game requires the user to draw a symbol on screen using LineRenderer. Once the symbol is drawn, if it is the correct symbol, a texture of the symbol will fade in.

I've tried placing a mesh on scene and toggling the alpha. But I will have to do the same for every other symbol that is drawn and placing in the scene. As it is also a running game similar to cave run and others, this would mean that the symbols will also be following the player and camera which I believe will cause a bit of lag issue in the game.

I don't really want to use OnGUI() as it will be updating every frame and I already have a lot of Updates() running at the same time from other scripts.

Any suggestions?