This has been a problem since launch. At the start we hoped the situation would improve when the servers came to Europe: they moved, the problem stayed.
Towards the end of last year it significantly improved but given the large influx of players (mostly 'returners' I expect) the problem has simply returned 'full monty'.
ZOS have never said much about it, I suspect it's simply a result of their 'mega-server' tech and something we'll just have to live with; like never-ending loading screens, or unplayable lag in Cyrodiil for the PVPers.