The location of the data center may dramatically increase player latency, and the default servers suggested may not be on the closest data center to you, increasing the amount of hops it takes to move data.
I’m still having issues, running on Shaw.
The realm(s) my characters are on turns out to be the eastern data centers (new york, I believe). My home ping is consistently under 50 ms, and the delays while looting or casting spells felt like a good 2 seconds and, sure enough, the world latency is showing at 176 ms.
I only just thought to look into testing a California data center server (I live in Vancouver,BC), and my latency is almost perfect on a brief test running a level 1 to stormwind. Latency sits at under 50 for home and world. I will continue to level over the next week and hopefully find consistent, smooth gameplay.
Where I’m sad is that if switching data centers is my fix, I’ve an east server with my hord and east server with my alliance characters - which I would be giving up, as character transfers would be beyond my means. Yay for BFA quick leveling, though! I’ll just be delayed getting fast flying.
The relevance of this, if it resolves my issue, isnt the personal solution it provides me, but the important question of why I was on the eastern data center to begin with. When first logging in on my account, many moons ago, the realm list provided low population options first (Filtered for PvE) - which I incorrectly assumed was being suggested based on location and population.