First time flipbook is loaded it is horribly pixelated, how to I remove that effect/preload the flipbook?

In my FPS I use Flipbooks to show the weapon graphics, using the Set flipbook node to switch between animations and weapons. If you start up the game, each time a flipbook is shown for the first time, it is heavily pixelated for a second. When the flipbook is loaded again, this effect is gone.

How do I remove this effect?