PUBG has been out on Xbox for over a year now. The devs have been working on improving the game but it still has issues loading building. This is especially apparent on Vikendi when landing castle. The one solution that improves performance, is an external SSD. This allows you to load buildings and guns quicker. It also appears to prevent glitches when driving across the map when objects fail to load.
Lots of players now are using SSD’s so you are at a real disadvantage if you do not. For around $50, I highly recommend getting an SSD. Here is a tutorial on how to transfer games to the SSD.