Flicker when resizing form

I have performance issue, all my diagram repaint everytime I resizing my main form. 

I tried the demo, put 4-5 blocks then do the resizing and it just fine, no repetitive repainting.

But when I make my own diagram, put 4-5 blocks, resize Form then the diagram will keep repainting until I done resizing my Form. Looks like a flicker. I'm sure there some property needs to be set, but where?

It may also depend if your diagram is inside some panel/scrollbox or any other container that forces repainting of all child controls? Is that your case?