Pre-caching images

My project has one component that generates CZML, and passes it to another component which passes it to Cesium.processCzml(). The CZML has a series of images to be drawn on Polygons, with different Availability times. Cesium correctly loads this, and allows me to Play and Pause, etc., all as I expect.

The problem is that as I Play it, I see significant flashing (just the first time a section is played). The flashing first shows a white box (I assume, while the image is loading from the server), and then the image appears (I assume, once it's downloaded). Once I've played through a section of time, there is no flashing the next time through (which I assume is because the images are now cached).

Is there a way for me to pre-cache the images (or anything else), to avoid the flashing? I'm willing to make the user wait a bit initially, for the better experience.

P.S. I tried calling Cesium.loadImage() on each URL when loading the CZML, and saw them all load over the network - but I still saw the same flashing when playing them (the first time).

You can embed the images in the CZML as data URIs, simple.czml (which ships with Cesium) does this. That means that the images are all guaranteed to be loaded when the CZML is.