In App Designer assigning an image to the image UI is very slow?

Im working on an image processing application using App Designer in 2019a.

I use the new image controller to display the end result like this:

app.imgFilter1.ImageSource=app.filteredImageFirst;

Now my problem is that just assigning an image to the controller takes easily 1-2 seconds for a 1920x1080 16bits per color channel. Is this normal?

Is there any way of making it faster, maybe using the axes controller? I shiver at what would happen if I assign an 4k image sized 4096x2160

Andreas