Render to minimap on command

I am trying to create a simple minimap. If I create a camera that looks down on the scene and renders continuously, my frame rate is dropped to 15 fps, just because of the extra graphics having to be rendered. My solution is to instantiate a camera every 0.5 second to take a picture for the minimap. For some reason, I can’t get this code to work. The minimap on the UI is always black, or always white.

 RenderTexture renderTex = new RenderTexture(200, 200, 1000);

 void RenderMinimap() {
	Camera minimapCam = null;
	GameObject go = new GameObject("MinmapCam", typeof(Camera));
	minimapCam = go.GetComponent<Camera>();
	minimapCam.transform.position = transform.position + Vector3.up*100; //move above the player
	minimapCam.transform.rotation = Quaternion.Euler(90, 0, 0); //look down
	minimapCam.orthographic = true;
	minimapCam.clearFlags = CameraClearFlags.SolidColor;
	minimapCam.farClipPlane = 3000;
	minimapCam.nearClipPlane = 0.1f;
	minimapCam.backgroundColor = new Color(255, 0, 120);
	minimapCam.orthographicSize = 20;
	minimapCam.targetTexture = renderTex;
	
	minimapCam.Render();
	
	GameObject.Find("Canvas/Minimap").GetComponent<RawImage>().texture = renderTex;
	
	DestroyImmediate(go);
	print ("Render");
}

A few hours later, I figured out how to do it. This is the new code:

 InvokeRepeating("RenderMinimap", 0.2f, 0.2f);

 void RenderMinimap() {
	Camera minimapCam = null;
	GameObject go = new GameObject("MinmapCam", typeof(Camera));
	minimapCam = go.GetComponent<Camera>();
	minimapCam.transform.position = transform.position + Vector3.up*100;
	minimapCam.transform.rotation = Quaternion.Euler(90, 0, 0);
	minimapCam.orthographic = true;
	minimapCam.clearFlags = CameraClearFlags.SolidColor;
	minimapCam.farClipPlane = 1000;
	minimapCam.nearClipPlane = 0.1f;
	minimapCam.backgroundColor = new Color(255, 0, 120);
	minimapCam.orthographicSize = 10;
	
	RenderTexture renderTex = new RenderTexture(100, 100, 100);
	minimapCam.targetTexture = renderTex;
	
	minimapCam.Render();
	
	RenderTexture.active = renderTex;
	Texture2D tex = new Texture2D(renderTex.width, renderTex.height);
	tex.ReadPixels(new Rect(0, 0, renderTex.width, renderTex.height), 0, 0);
	tex.Apply();
	RenderTexture.active = null;
	
	GameObject.Find("Canvas/Minimap").GetComponent<RawImage>().texture = tex;
	
	DestroyImmediate(go);
}