Before I knew this was a game wide issue I was only having this problem on SC so I actually put in a ticket and asked for free character transfers off the server. Of course they said they couldn’t do that, I expected that but you never know right? Anyway, this is one sentence from the response I got from the GM:
_As well, we’d definitely appreciate your reports about latency on Scarlet Crusade as soon as it happens. There’s a persistent technical issue that’s been ongoing for a while where the servers act up, and it’s been very resistant to our fixes. This post has more information on what’s going on and how to report it: https://us.forums.blizzard.com/en/wow/t/known-technical-support-issues-updated-may-18-2019/22909/5_
Ok so “it’s been very resistant to our fixes” tells me they really do not know why it is happening. That isn’t a good sign IMO to ever getting this fixed. Now, just a few days ago I had a weird rollback happen on Turalyon, a GM even confirmed it happened because it made a quest item become “stuck” so he had to unstick it so it could apply to an achievement. The post I made about it in CS is here Is My Toon Bugging? and if you check my final post you’ll see it happened again. I can’t help but think it is related to this “persistent technical issue” causing the lag with no lag.