Building floors swapping textures

[Mattk50]

Occasionally when inside a bulding the game freezes momentarily and then the floor textures switches from wood planking to metal diamond plate or vice versa. When this happens, some of the traders in the building flicker and sometimes they vanish for 2-3 seconds. When that happens at the end of the 3 seconds when they re-appear the floor texture usually goes back to what it was before, which makes me guess that the floor texture is somehow defined by the type of traders in the shop. This can also happen when you open a shop window.