Seems like this began happening right at the time the client update was released a few days ago. Everyone (players and NPCs) not within 10-20 yards from you will phase in and out on what seems to be 5 second intervals, there is a good 3-5 second delay between button press and actual cast. This is happening in all areas too, even main cities. I asked general chat in durotar to confirm that it wasn't just me experiencing this, lo and behold, 4 people piped up stating that i wasn't alone.
Not sure if these numbers matter, but latency was as follows-
Home- 560ms
World- 545ms
I have only had latency errors in the past when im flying around in orgrimmar at peak hours of the day.
I checked on The Venture Co. server just to see if it wasn't just another CRZ issue (Venture Co. has CRZ disabled), it turned out it was not, as that server was affected as well.
I just came here to ask if your server is acting strange as Area 52?