Sometimes cells don't render properly, it has been a rare sporadic issue since Oblivion single player. If it is consistent in one area, try a game repair.

This is also seen when first logging in, and your system is either unable to render quickly enough of the environment around. But I have seen it at times with changing zones. Usually in Cyrodil.

Going on the cache file theory - to be forward it is a database file if I am not mistaken (someone correct me though) and databases as I have seen even as simple as the cache file can become corrupt with too much data.

This is a client side issue rendering in general fast enough the data sent thru the "pipe"/Internet connection etc. Unsure if this is to be resolved with the expected revamp of the memory leak issues. And possible rework of many parts of the UI in the coming months.