I played nonstop from the time the server came up until about an hour ago when i broke for dinner. Non-stop no issues no lag gained 6 levels, didn't sleep, 4 monster energy drinks.
That was 2am - 6:30pm my time where all was wonderful and worked pretty well. Seems like we hit a big rush of people coming on and the servers can't keep up.
And around 3am I was looking for group to do the 3 group dungeons and waited about 20 minutes to find enough people to group. My guild was about 50/500 online instead of the usual 200/500.
Lots of things point to load. So no, I don't agree that it would still have the same issues.