How to draw simplex noise fast on JavaFX canvas?

Question

I'm using Kurt Spencer's implementation of OpenSimplexNoise found here.

I'm trying to draw the resulting noise on a 512x52 JavaFX Canvas as fast as possible.

Note: Not shown in the code below for simplicity, the draw functions takes in a zoom level (the value of a JavaFX Slider element). The draw function is called from a change listener on that slider.

What I've Tried

GraphicsContext setFill() and fillRect()

Using the value of the noise to set the fill, and then calling fillRect() for a 1x1 rectangle at the appropriate location:

public void drawWithRect() {
    // width and height of the canvas
    int width = (int)getCanvas().getWidth();
    int height = (int)getCanvas().getHeight();

    // Get the graphics context of the canvas
    GraphicsContext gc = getCanvas().getGraphicsContext2D();

    for (int y = 0; y < height; y++) {
        for (int x = 0; x < width; x++) {
            double val = (noise((double)x/40, (double)y/40));
            gc.setFill(Color.color(val,val,val));
            gc.fillRect(x,y,1,1);
        }
    }
}

Result: Despite apparantly taking 40ms roughly, this seriously lags my computer, taking 5+ seconds at a time for the results to display. This was bad. I'm unsure what was going on behind the scenes here to cause the program to have difficulty rendering it all...

Using a PixelWriter

My next improvement came from using a PixelWriter:

public void drawWithPixelWriter() {
    // width and height of the canvas
    int width = (int)getCanvas().getWidth();
    int height = (int)getCanvas().getHeight();

    // Get the graphics context of the canvas
    GraphicsContext gc = getCanvas().getGraphicsContext2D();

    // Create the PixelWriter
    PixelWriter pixelWriter = gc.getPixelWriter();

    for (int y = 0; y < height; y++) {
        for (int x = 0; x < width; x++) {
            double val = (noise((double)x/40, (double)y/40));
            pixelWriter.setColor(x,y, Color.color(val,val,val));
        }
    }
}

Result: 25ms on average. This is much better. There is no real lag and the application feels smoothish and responsive.

Writing using a PixelFormat

We use PixelFormat.getByteRgbInstance(); and write the values of our noise into a large byte array, which is then passed to the pixelWriter along with the PixelFormat.

public void drawWithPixelFormat() {
    // width and height of the canvas
    int width = (int)getCanvas().getWidth();
    int height = (int)getCanvas().getHeight();

    // array to hold rgb value for every pixel
    byte[] pixels = new byte[height * width * 3];

    // Get the graphics context of the canvas
    GraphicsContext gc = getCanvas().getGraphicsContext2D();

    // Create the PixelWriter
    PixelWriter pixelWriter = gc.getPixelWriter();

    // Define the PixelFormat
    PixelFormat<ByteBuffer> pixelFormat = PixelFormat.getByteRgbInstance();

    for (int y = 0; y < height; y++) {
        for (int x = 0; x < width; x++) {
            // Get the index
            int i = y * width * 3 + x * 3;
            //Get the noise value
            byte val = (byte)(noise((double)x/40, (double)y/40)*255);
            // set the rgb colors of the pixel;
            pixels[i] = val;
            pixels[i + 1] = val;
            pixels[i + 2] = val;
        }
    }
    // draw the noise
    pixelWriter.setPixels(0, 0, width, height, pixelFormat, pixels, 0, width * 3);
}

Result: 16ms average for each draw. This is much better and for a 512x512 it is very smooth. See here for gif.

But what if I want to generate bigger maps? For a 1024x1024 canvas the draw time is around 65ms and noticable choppy. What if I want to add a number of octaves or change the color based on some conditions? All this would add to the draw time so It's imperative I bring it down as much as possible.

Any suggestions for improvements?