I think the issue coming on "lower systems performance" if you have a table with more loading and rendering time you get that issue, i powered up my system with a
gtx 1070 ti and the issue is gone. My GPU before was a GTX 1060 6 GB, in 4k. Loading Time over 25 sec you get sometimes not the BG, you see that, in PBX the small Window popup for loading/rendering/script came for a short time over the pbx loading screen before the playfield is showing.
Sorry for my bad english