Unity Hololens Asset streaming optimization

Question

I'm working on a Hololens app that displays a PNG image with info for the user. The images are loaded from a StreamingAssets folder in a coroutine. The issue lies in the speed at which these assets are loaded. If the user cycles to another page, the app momentarily drops to about 1-3 FPS on a PC.

What I hope some of you can help me with is think of ways to optimize the storage and streaming of these images. Is there a way to for example, load the image in a lower resolution to save on time and memory (with the hardware's very limited memory) and load in the additional detail when it actually needs to be displayed? Would multi-threading make the framerate better while loading the image?

Answer 1

So Programmer's suggestion in the comments helped eliminate the performance issues completely. The code down below is the coroutine that is used to stream in the required image(s) upon startup.

IEnumerator LoadImages()
{
    int oldImgIndx = imageIndex;
    imageIndex = 1;

    bool thereAreImages = true;
    while (thereAreImages && imageIndex < 1000)
    {
        if (System.IO.File.Exists(CreateFilePath(imageIndex)))
        {
            string url = "File:///" + CreateFilePath(imageIndex);
            Texture2D tex = new Texture2D(4, 4);
            WWW www = new WWW(url);
            yield return www;
            www.LoadImageIntoTexture(tex);
            spriteList.Add(Sprite.Create(tex, new Rect(0, 0, tex.width, tex.height), new Vector2(0.5f, 0.5f)));
            imageIndex++;
        }
        else
        {
            thereAreImages = false;
        }
    }
    finished = true;
    imageIndex = oldImgIndx;
}

The issue on the Hololens lies in the www.LoadImageIntoTexture(tex); line. This code is required when displaying multiple images on the PC side of things, however on the Hololens, where only one image is displayed at a time it can be left out.