We are still looking at this one. We have not been able to repro on other Samsung tablets like SM-T321 / 4.4.2 or SM-T900 / 4.4.2. Also, as your experience matches, it does not repro on non-Samsung tablets.
Throughout this investigation, however, we have been able to fix the white-screen / slow-loading part of the issue, and I'll do my best to explain that here:
A complete content load involves two phases - the first phase brings up a low-res version of the content, and that should happen immediately (in most cases, this happens off-screen, so the content is just there when you scroll to it). The second phase brings up a high-res version of the content, and that is the version that will look crisp and contain interactivity. In many cases, you may not notice the two phases, because the transition happens as you're scrolling around and deciding which content to interact with. By the time a reader settles on content, it's the high-res, interactive portion with which they're interacting. In attempting to reproduce this particular issue, we have seen the display go from an empty, white screen directly to the high-res, interactive content. That means the first phase is not working.
We have a fix pending for that portion of the issue, and that means that readers will no longer see a empty, white screen while the high-res version loads. However, I understand that this is not the entirety of your issue.