Sadly no real update or solutions at the moment - this seems to be a problem that was introduced with Nvidia drivers of version 445.xx onwards. As of version 446.xx there has been some improvement for a few players, but there are still reports coming in (meaning there are likely some particular hardware-constellations that are still affected). The issue is also apparently not limited to WoW but manifests in different ways in multiple games, so unfortunately chances are nothing we could feasibly do will actually fully resolve this.